View source for Generalised floating point multiplication

{{Template:Draft task}}
Use the [[Generalised floating point addition]] template to implement generalised floating point multiplication for a
[[wp:Balanced ternary|Balanced ternary]] test case.

'''Test case details''':
Balanced ternary is a way of representing numbers.  Unlike the prevailing binary representation, a balanced ternary "real" is in base 3, and each digit can have the values 1, 0, or −1.  For example, decimal 11 = 3<sup>2</sup> + 3<sup>1</sup> − 3<sup>0</sup>, thus can be written as "++−", while 6 = 3<sup>2</sup> − 3<sup>1</sup> + 0 × 3<sup>0</sup>, i.e., "+−0" and for an actual real number 6⅓ the ''exact'' representation is 3<sup>2</sup> − 3<sup>1</sup> + 0 × 3<sup>0</sup> + 1 × 3<sup>-1</sup> i.e., "+−0.+"

For this task, implement balanced ternary representation of real numbers with the following:

'''Requirements'''
# Support arbitrary precision real numbers, both positive and negative;
# Provide ways to convert to and from text strings, using digits '+', '-' and '0' (unless you are already using strings to represent balanced ternary; but see requirement 5).
# Provide ways to convert to and from native integer and real type (unless, improbably, your platform's native integer type ''is'' balanced ternary).  If your native integers can't support arbitrary length, overflows during conversion must be indicated.
# Provide ways to perform addition, negation and multiplication directly on balanced ternary integers; do ''not'' convert to native integers first.
# Make your implementation efficient, with a reasonable definition of "efficient" (and with a reasonable definition of "reasonable").
# The Template should successfully handle these multiplications in other bases.  In particular  [[wp:Septemvigesimal|Septemvigesimal]] and "Balanced base-27".

Optionally:
* For faster ''long'' multiplication use [[wp:Karatsuba_algorithm|Karatsuba algorithm]]. 
* Using the Karatsuba algorithm, spread the computation across multiple CPUs.

'''Test case 1''' - With balanced ternaries ''a'' from string "+-0++0+.+-0++0+", ''b'' from native real -436.436, ''c'' "+-++-.+-++-":
* write out ''a'', ''b'' and ''c'' in decimal notation.
* calculate ''a'' × (''b'' − ''c''), write out the result in both ternary and decimal notations.
* In the above limit the precision to 81 ternary digits after the point.

'''Test case 2''' - Generate a multiplication table of balanced ternaries where the rows of the table are for a 1st factor of 1 to 27, and the column of the table are for the second factor of 1 to 12.

Implement the code in a generalised form (such as a [[wp:Template (programming)|Template]], [[wp:Modular programming|Module]] or [[wp:Mixin|Mixin]] etc) that permits reusing of the code for different [[wp:Base_(exponentiation)#In_numeral_systems|Bases]].

If it is not possible to implement code in syntax of the specific language then:
* note the reason.
* perform the ''test case'' using a built-in or external library.
<!--
'''Test case:'''

Use the Template to define [[wp:Arbitrary-precision arithmetic|Arbitrary precision multiplication]] on numbers stored in Balanced Ternary. 

{|class="wikitable" style="text-align: center; margin: 1em auto 1em auto;"
|+ Calculate the terms for -7 to 21 in this sequence of calculations
|-
! Number !! Term calculation !! Result
|-
| -7 || 111111111e63**2 x 81 + 2e135 - 1e126 || 1e144
|-
| -6 || 111111111111111111e54**2 x 81 + 2e126 - 1e108 || 1e144
|-
| -5 || 111111111111111111111111111e45**2 x 81 + 2e117 - 1e90 || 1e144
|-
| -4 || 111111111111111111111111111111111111e36**2 x 81 + 2e108 - 1e72 || 1e144
|-
| etc. || The last calculation will be with floating point numbers of more then 500 digits  || 1e144
|}
Note: The results will always be 1e144.
-->
=={{header|ALGOL 68}}==
{{works with|ALGOL 68|Revision 1 - one minor extension to language used - PRAGMA READ, similar to C's #include directive.}}
{{works with|ALGOL 68G|Any - tested with release [http://sourceforge.net/projects/algol68/files/algol68g/algol68g-2.3.3 algol68g-2.3.3].}}
{{wont work with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release [http://sourceforge.net/projects/algol68/files/algol68toc/algol68toc-1.8.8d/algol68toc-1.8-8d.fc9.i386.rpm/download 1.8-8d] - due to extensive use of '''format'''[ted] ''transput''.}}
'''File: Template.Big_float.Multiplication.a68'''<syntaxhighlight lang="algol68">##########################################
#               TASK CODE                #
# Actual generic mulitplication operator #
##########################################
# Alternatively use http://en.wikipedia.org/wiki/Karatsuba_algorithm #

OP * = (DIGITS a, b)DIGITS: (
  DIGITS minus one = -IDENTITY LOC DIGITS,
         zero = ZERO LOC DIGITS,
         one = IDENTITY LOC DIGITS;
  INT order = digit order OF arithmetic;
  IF SIGN a = 0 OR SIGN b = 0 THEN zero
CO # Note: The following require the inequality operators #
  ELIF a = one THEN b
  ELIF b = one THEN a
  ELIF a = minus one THEN -b
  ELIF b = minus one THEN -a
END CO
  ELSE
    DIGIT zero = ZERO LOC DIGIT;
    DIGIT one =  IDENTITY LOC DIGIT;
    [order + MSD a+MSD b: LSD a+LSD b]DIGIT a x b;

    FOR place FROM LSD a+LSD b BY order TO LSD a+MSD b DO
      a x b[place] := zero # pad the MSDs of the result with Zero #
    OD;
    FOR place a FROM LSD a BY order TO MSD a DO
      DIGIT digit a = a[place a];
      DIGIT carry := zero;
      FOR place b FROM LSD b BY order TO MSD b DO
        DIGIT digit b = b[place b];
        REF DIGIT digit ab = a x b[place a + place b];
        IF carry OF arithmetic THEN # used for big number arithmetic #
          MOID(carry := ( digit ab +:= carry ));
          DIGIT prod := digit a;
          MOID(carry +:= ( prod *:= digit b ));
          MOID(carry +:= ( digit ab +:= prod ))
        ELSE # carry = 0 so we can just ignore the carry #
          DIGIT prod := digit a;
          MOID(prod *:= digit b);
          MOID(digit ab +:= prod)
        FI
      OD;
      a x b[place a + MSD b + order] := carry
    OD;
    INITDIGITS a x b # normalise #
  FI
);

######################################
#  Define the hybrid multiplication  #
# operators for the generalised base #
######################################

OP * = (DIGIT a, DIGITS b)DIGITS: INITDIGITS a * b;
OP * = (DIGITS a, DIGIT b)DIGITS: a * INITDIGITS b;

OP *:= = (REF DIGITS lhs, DIGIT arg)DIGITS: lhs := lhs * INITDIGITS arg;
</syntaxhighlight>'''File: Template.Balanced_ternary_float.Base.a68'''<syntaxhighlight lang="algol68">PR READ "Template.Big_float_BCD.Base.a68" PR # [[rc:Generalised floating point addition]] #

################################################################
# First: define the attributes of the arithmetic we are using. #
################################################################
arithmetic := (
  # balanced = # TRUE, 
  # carry = # TRUE, 
  # base = # 3, # width = # 1, # places = # 81, # order = # -1, 
  # repr = # USTRING("-","0","+")[@-1]
);

OP INITDIGIT = (CHAR c)DIGIT: (
  DIGIT out;
  digit OF out :=
    IF   c = "+" THEN +1
    ELIF c = "0" THEN  0
    ELIF c = "-" THEN -1
    ELSE raise value error("Unknown digit :"""+c+""""); SKIP
    FI;
  out
);

OP INITBIGREAL = (STRING s)BIGREAL: (
  BIGREAL out;
  BIGREAL base of arithmetic = INITBIGREAL base OF arithmetic; # Todo: Opt #
  INT point := UPB s; # put the point on the extreme right #
  FOR place FROM LWB s TO UPB s DO
    IF s[place]="." THEN
      point := place
    ELSE
      out := out SHR digit order OF arithmetic + INITDIGIT s[place]
    FI
  OD;
  out SHR (UPB s-point)
);</syntaxhighlight>'''File: test.Balanced_ternary_float.Multiplication.a68'''<syntaxhighlight lang="algol68">#!/usr/local/bin/a68g --script #
####################################################################
# A program to test arbitrary length floating point multiplication #
####################################################################

PR READ "prelude/general.a68" PR  # [[rc:Template:ALGOL 68/prelude]] #

PR READ "Template.Big_float.Multiplication.a68" PR

# include the basic axioms of the digits being used #
PR READ "Template.Balanced_ternary_float.Base.a68" PR

PR READ "Template.Big_float.Addition.a68" PR # [[rc:Generalised floating point addition]] #
PR READ "Template.Big_float.Subtraction.a68" PR # [[rc:Generalised floating point addition]] #

test1:( # Basic arithmetic #
  INT rw = long real width;
  BIGREAL a = INITBIGREAL "+-0++0+.+-0++0+", # 523.239... #
          b = INITBIGREAL - LONG 436.436,
          c = INITBIGREAL "+-++-.+-++-"; # 65.267... #
  printf(($g 9k g(rw,rw-5)39kgl$,
    "a =",INITLONGREAL a, REPR a,
    "b =",INITLONGREAL b, REPR b,
    "c =",INITLONGREAL c, REPR c,
    "a*(b-c)",INITLONGREAL(a*(b-c)), REPR(a*(b-c)),
  $l$))
);

test2:( # A floating point Ternary multiplication table #
  FORMAT s = $"|"$; # field seperator #

  INT lwb = 1, tab = 8, upb = 12;

  printf($"# "f(s)" *   "f(s)$);
  FOR j FROM lwb TO upb DO
    FORMAT col = $n(tab)k f(s)$;
    printf(($g" #"g(0)f(col)$, REPR INITBIGREAL j,j))
  OD;
  printf($l$);
  FOR i FROM lwb TO 27 DO
    printf(($g(0) 3k f(s) g 9k f(s)$,i,REPR INITBIGREAL i));
    FOR j FROM lwb TO i MIN upb DO
      FORMAT col = $n(tab)k f(s)$;
      BIGREAL product = INITBIGREAL i * INITBIGREAL j;
      printf(($gf(col)$, REPR product))
    OD;
    IF upb > i THEN printf($n(upb-i)(n(tab-1)x f(s))$) FI;
    printf($l$)
  OD
)</syntaxhighlight>'''Output:'''
<pre>
a =     +523.23914037494284407864655  +-0++0+.+-0++0+
b =     -436.43600000000000000000000  -++-0--.--0+-00+++-0-+---0-+0++++0--0000+00-+-+--+0-0-00--++0-+00---+0+-+++0+-0----0++
c =      +65.26748971193415637860082  +-++-.+-++-
a*(b-c) -262510.90267998140903693919  ----000-0+0+.0+0-0-00---00--0-0+--+--00-0++-000++0-000-+0+-----+++-+-0+-+0+0++0+0-++-++0+---00++++

# | *   |+ #1   |+- #2  |+0 #3  |++ #4  |+-- #5 |+-0 #6 |+-+ #7 |+0- #8 |+e+- #9|+0+ #10|++- #11|++0 #12|
1 |+    |+      |       |       |       |       |       |       |       |       |       |       |       |
2 |+-   |+-     |++     |       |       |       |       |       |       |       |       |       |       |
3 |+0   |+0     |+-0    |+e+-   |       |       |       |       |       |       |       |       |       |
4 |++   |++     |+0-    |++0    |+--+   |       |       |       |       |       |       |       |       |
5 |+--  |+--    |+0+    |+--0   |+-+-   |+0-+   |       |       |       |       |       |       |       |
6 |+-0  |+-0    |++0    |+-e+-  |+0-0   |+0+0   |++e+-  |       |       |       |       |       |       |
7 |+-+  |+-+    |+---   |+-+0   |+00+   |++0-   |+---0  |+--++  |       |       |       |       |       |
8 |+0-  |+0-    |+--+   |+0-0   |++--   |++++   |+--+0  |+-0+-  |+-+0+  |       |       |       |       |
9 |+e+- |+e+-   |+-e+-  |+e+0   |++e+-  |+--e+- |+-e+0  |+-+e+- |+0-e+- |+e++   |       |       |       |
10|+0+  |+0+    |+-+-   |+0+0   |++++   |+-0--  |+-+-0  |+0--+  |+000-  |+0+e+- |++-0+  |       |       |
11|++-  |++-    |+-++   |++-0   |+--0-  |+-00+  |+-++0  |+00--  |+0+-+  |++-e+- |++0+-  |+++++  |       |
12|++0  |++0    |+0-0   |++e+-  |+--+0  |+-+-0  |+0-e+- |+00+0  |++--0  |++e+0  |++++0  |+--0-0 |+--+e+-|
13|+++  |+++    |+00-   |+++0   |+-0-+  |+-++-  |+00-0  |+0+0+  |++0--  |+++e+- |+---++ |+--+0- |+-0-+0 |
14|+--- |+---   |+00+   |+---0  |+-0+-  |+0--+  |+00+0  |++-0-  |++0++  |+---e+-|+--+-- |+-0-0+ |+-0+-0 |
15|+--0 |+--0   |+0+0   |+--e+- |+-+-0  |+0-+0  |+0+e+- |++0-0  |++++0  |+--e+0 |+-0--0 |+-00+0 |+-+-e+-|
16|+--+ |+--+   |++--   |+--+0  |+-+0+  |+000-  |++--0  |++0++  |+---+- |+--+e+-|+-00-+ |+-+--- |+-+0+0 |
17|+-0- |+-0-   |++-+   |+-0-0  |+0---  |+00++  |++-+0  |++++-  |+--00+ |+-0-e+-|+-0+0- |+-+0-+ |+0---0 |
18|+-e+-|+-e+-  |++e+-  |+-e+0  |+0-e+- |+0+e+- |++e+0  |+---e+-|+--+e+-|+-e++  |+-+-e+-|+-++e+-|+0-e+0 |
19|+-0+ |+-0+   |+++-   |+-0+0  |+0-++  |++---  |+++-0  |+--0-+ |+-0-0- |+-0+e+-|+-+00+ |+0--+- |+0-++0 |
20|+-+- |+-+-   |++++   |+-+-0  |+000-  |++-0+  |++++0  |+--+-- |+-00-+ |+-+-e+-|+-+++- |+0-0++ |+000-0 |
21|+-+0 |+-+0   |+---0  |+-+e+- |+00+0  |++0-0  |+---e+-|+--++0 |+-0+-0 |+-+e+0 |+0--+0 |+00--0 |+00+e+-|
22|+-++ |+-++   |+--0-  |+-++0  |+0+-+  |++0+-  |+--0-0 |+-0-0+ |+-+--- |+-++e+-|+0-0++ |+0000- |+0+-+0 |
23|+0-- |+0--   |+--0+  |+0--0  |+0++-  |+++-+  |+--0+0 |+-000- |+-+-++ |+0--e+-|+00--- |+00+0+ |+0++-0 |
24|+0-0 |+0-0   |+--+0  |+0-e+- |++--0  |++++0  |+--+e+-|+-0+-0 |+-+0+0 |+0-e+0 |+000-0 |+0+-+0 |++--e+-|
25|+0-+ |+0-+   |+-0--  |+0-+0  |++-0+  |+---0- |+-0--0 |+-0+++ |+-+++- |+0-+e+-|+00+-+ |+0++-- |++-0+0 |
26|+00- |+00-   |+-0-+  |+00-0  |++0--  |+---++ |+-0-+0 |+-+-+- |+0--0+ |+00-e+-|+0+-0- |++---+ |++0--0 |
27|+e+0 |+e+0   |+-e+0  |+e++   |++e+0  |+--e+0 |+-e++  |+-+e+0 |+0-e+0 |+e+--  |+0+e+0 |++-e+0 |++e++  |

</pre>

=={{header|Go}}==
{{trans|Phix}}
In the interests of brevity many of the comments and all of the commented-out code has been omitted.
<syntaxhighlight lang="go">package main

import (
    "fmt"
    "log"
    "math"
    "strings"
)

const (
    maxdp           = 81
    binary          = "01"
    ternary         = "012"
    balancedTernary = "-0+"
    decimal         = "0123456789"
    hexadecimal     = "0123456789ABCDEF"
    septemVigesimal = "0123456789ABCDEFGHIJKLMNOPQ"
    balancedBase27  = "ZYXWVUTSRQPON0ABCDEFGHIJKLM"
    base37          = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
)

/* helper functions */

func changeByte(s string, idx int, c byte) string {
    bytes := []byte(s)
    bytes[idx] = c
    return string(bytes)
}

func removeByte(s string, idx int) string {
    le := len(s)
    bytes := []byte(s)
    copy(bytes[idx:], bytes[idx+1:])
    return string(bytes[0 : le-1])
}

func insertByte(s string, idx int, c byte) string {
    le := len(s)
    t := make([]byte, le+1)
    copy(t, s)
    copy(t[idx+1:], t[idx:])
    t[idx] = c
    return string(t)
}

func prependByte(s string, c byte) string {
    le := len(s)
    bytes := make([]byte, le+1)
    copy(bytes[1:], s)
    bytes[0] = c
    return string(bytes)
}

func abs(i int) int {
    if i < 0 {
        return -i
    }
    return i
}

// converts Phix indices to Go
func gIndex(pIndex, le int) int {
    if pIndex < 0 {
        return pIndex + le
    }
    return pIndex - 1
}

func getCarry(digit, base int) int {
    if digit > base {
        return 1
    } else if digit < 1 {
        return -1
    }
    return 0
}

// convert string 'b' to a decimal floating point number
func b2dec(b, alphabet string) float64 {
    res := 0.0
    base := len(alphabet)
    zdx := strings.IndexByte(alphabet, '0') + 1
    signed := zdx == 1 && b[0] == '-'
    if signed {
        b = b[1:]
    }
    le := len(b)
    ndp := strings.IndexByte(b, '.') + 1
    if ndp != 0 {
        b = removeByte(b, ndp-1) // remove decimal point
        ndp = le - ndp
    }
    for i := 1; i <= len(b); i++ {
        idx := strings.IndexByte(alphabet, b[i-1]) + 1
        res = float64(base)*res + float64(idx) - float64(zdx)
    }
    if ndp != 0 {
        res /= math.Pow(float64(base), float64(ndp))
    }
    if signed {
        res = -res
    }
    return res
}

// string 'b' can be balanced or unbalanced
func negate(b, alphabet string) string {
    if alphabet[0] == '0' {
        if b != "0" {
            if b[0] == '-' {
                b = b[1:]
            } else {
                b = prependByte(b, '-')
            }
        }
    } else {
        for i := 1; i <= len(b); i++ {
            if b[i-1] != '.' {
                idx := strings.IndexByte(alphabet, b[i-1]) + 1
                gi := gIndex(-idx, len(alphabet))
                b = changeByte(b, i-1, alphabet[gi])
            }
        }
    }
    return b
}

func bTrim(b string) string {
    // trim  trailing ".000"
    idx := strings.IndexByte(b, '.') + 1
    if idx != 0 {
        b = strings.TrimRight(strings.TrimRight(b, "0"), ".")
    }
    // trim leading zeros but not "0.nnn"
    for len(b) > 1 && b[0] == '0' && b[1] != '.' {
        b = b[1:]
    }
    return b
}

// for balanced number systems only
func bCarry(digit, base, idx int, n, alphabet string) (int, string) {
    carry := getCarry(digit, base)
    if carry != 0 {
        for i := idx; i >= 1; i-- {
            if n[i-1] != '.' {
                k := strings.IndexByte(alphabet, n[i-1]) + 1
                if k < base {
                    n = changeByte(n, i-1, alphabet[k])
                    break
                }
                n = changeByte(n, i-1, alphabet[0])
            }
        }
        digit -= base * carry
    }
    return digit, n
}

// convert a string from alphabet to alphabet2
func b2b(n, alphabet, alphabet2 string) string {
    res, m := "0", ""
    if n != "0" {
        base := len(alphabet)
        base2 := len(alphabet2)
        zdx := strings.IndexByte(alphabet, '0') + 1
        zdx2 := strings.IndexByte(alphabet2, '0') + 1
        var carry, q, r, digit int
        idx := strings.IndexByte(alphabet, n[0]) + 1
        negative := (zdx == 1 && n[0] == '-') || (zdx != 1 && idx < zdx)
        if negative {
            n = negate(n, alphabet)
        }
        ndp := strings.IndexByte(n, '.') + 1
        if ndp != 0 {
            n, m = n[0:ndp-1], n[ndp:]
        }
        res = ""
        for len(n) > 0 {
            q = 0
            for i := 1; i <= len(n); i++ {
                digit = strings.IndexByte(alphabet, n[i-1]) + 1 - zdx
                q = q*base + digit
                r = abs(q) % base2
                digit = abs(q)/base2 + zdx
                if q < 0 {
                    digit--
                }
                if zdx != 1 {
                    digit, n = bCarry(digit, base, i-1, n, alphabet)
                }
                n = changeByte(n, i-1, alphabet[digit-1])
                q = r
            }
            r += zdx2
            if zdx2 != 1 {
                r += carry
                carry = getCarry(r, base2)
                r -= base2 * carry
            }
            res = prependByte(res, alphabet2[r-1])
            n = strings.TrimLeft(n, "0")
        }
        if carry != 0 {
            res = prependByte(res, alphabet2[carry+zdx2-1])
        }
        if len(m) > 0 {
            res += "."
            ndp = 0
            if zdx != 1 {
                lm := len(m)
                alphaNew := base37[0:len(alphabet)]
                m = b2b(m, alphabet, alphaNew)
                m = strings.Repeat("0", lm-len(m)) + m
                alphabet = alphaNew
                zdx = 1
            }
            for len(m) > 0 && ndp < maxdp {
                q = 0
                for i := len(m); i >= 1; i-- {
                    digit = strings.IndexByte(alphabet, m[i-1]) + 1 - zdx
                    q += digit * base2
                    r = abs(q)%base + zdx
                    q /= base
                    if q < 0 {
                        q--
                    }
                    m = changeByte(m, i-1, alphabet[r-1])
                }
                digit = q + zdx2
                if zdx2 != 1 {
                    digit, res = bCarry(digit, base2, len(res), res, alphabet2)
                }
                res += string(alphabet2[digit-1])
                m = strings.TrimRight(m, "0")
                ndp++
            }
        }
        res = bTrim(res)
        if negative {
            res = negate(res, alphabet2)
        }
    }
    return res
}

// convert 'd' to a string in the specified base
func float2b(d float64, alphabet string) string {
    base := len(alphabet)
    zdx := strings.Index(alphabet, "0") + 1
    carry := 0
    neg := d < 0
    if neg {
        d = -d
    }
    res := ""
    whole := int(d)
    d -= float64(whole)
    for {
        ch := whole%base + zdx
        if zdx != 1 {
            ch += carry
            carry = getCarry(ch, base)
            ch -= base * carry
        }
        res = prependByte(res, alphabet[ch-1])
        whole /= base
        if whole == 0 {
            break
        }
    }
    if carry != 0 {
        res = prependByte(res, alphabet[carry+zdx-1])
        carry = 0
    }
    if d != 0 {
        res += "."
        ndp := 0
        for d != 0 && ndp < maxdp {
            d *= float64(base)
            digit := int(d) + zdx
            d -= float64(digit)
            if zdx != 1 {
                digit, res = bCarry(digit, base, len(res), res, alphabet)
            }
            res += string(alphabet[digit-1])
            ndp++
        }
    }
    if neg {
        res = negate(res, alphabet)
    }
    return res
}

func bAdd(a, b, alphabet string) string {
    base := len(alphabet)
    zdx := strings.IndexByte(alphabet, '0') + 1
    var carry, da, db, digit int
    if zdx == 1 {
        if a[0] == '-' {
            return bSub(b, negate(a, alphabet), alphabet)
        }
        if b[0] == '-' {
            return bSub(a, negate(b, alphabet), alphabet)
        }
    }
    adt := strings.IndexByte(a, '.') + 1
    bdt := strings.IndexByte(b, '.') + 1
    if adt != 0 || bdt != 0 {
        if adt != 0 {
            adt = len(a) - adt + 1
            gi := gIndex(-adt, len(a))
            a = removeByte(a, gi)
        }
        if bdt != 0 {
            bdt = len(b) - bdt + 1
            gi := gIndex(-bdt, len(b))
            b = removeByte(b, gi)
        }
        if bdt > adt {
            a += strings.Repeat("0", bdt-adt)
            adt = bdt
        } else if adt > bdt {
            b += strings.Repeat("0", adt-bdt)
        }
    }
    if len(a) < len(b) {
        a, b = b, a
    }
    for i := -1; i >= -len(a); i-- {
        if i < -len(a) {
            da = 0
        } else {
            da = strings.IndexByte(alphabet, a[len(a)+i]) + 1 - zdx
        }
        if i < -len(b) {
            db = 0
        } else {
            db = strings.IndexByte(alphabet, b[len(b)+i]) + 1 - zdx
        }
        digit = da + db + carry + zdx
        carry = getCarry(digit, base)
        a = changeByte(a, i+len(a), alphabet[digit-carry*base-1])
        if i < -len(b) && carry == 0 {
            break
        }
    }
    if carry != 0 {
        a = prependByte(a, alphabet[carry+zdx-1])
    }
    if adt != 0 {
        gi := gIndex(-adt+1, len(a))
        a = insertByte(a, gi, '.')
    }
    a = bTrim(a)
    return a
}

func aSmaller(a, b, alphabet string) bool {
    if len(a) != len(b) {
        log.Fatal("strings should be equal in length")
    }
    for i := 1; i <= len(a); i++ {
        da := strings.IndexByte(alphabet, a[i-1]) + 1
        db := strings.IndexByte(alphabet, b[i-1]) + 1
        if da != db {
            return da < db
        }
    }
    return false
}

func bSub(a, b, alphabet string) string {
    base := len(alphabet)
    zdx := strings.IndexByte(alphabet, '0') + 1
    var carry, da, db, digit int
    if zdx == 1 {
        if a[0] == '-' {
            return negate(bAdd(negate(a, alphabet), b, alphabet), alphabet)
        }
        if b[0] == '-' {
            return bAdd(a, negate(b, alphabet), alphabet)
        }
    }
    adt := strings.Index(a, ".") + 1
    bdt := strings.Index(b, ".") + 1
    if adt != 0 || bdt != 0 {
        if adt != 0 {
            adt = len(a) - adt + 1
            gi := gIndex(-adt, len(a))
            a = removeByte(a, gi)
        }
        if bdt != 0 {
            bdt = len(b) - bdt + 1
            gi := gIndex(-bdt, len(b))
            b = removeByte(b, gi)
        }
        if bdt > adt {
            a += strings.Repeat("0", bdt-adt)
            adt = bdt
        } else if adt > bdt {
            b += strings.Repeat("0", adt-bdt)
        }
    }
    bNegate := false
    if len(a) < len(b) || (len(a) == len(b) && aSmaller(a, b, alphabet)) {
        bNegate = true
        a, b = b, a
    }
    for i := -1; i >= -len(a); i-- {
        if i < -len(a) {
            da = 0
        } else {
            da = strings.IndexByte(alphabet, a[len(a)+i]) + 1 - zdx
        }
        if i < -len(b) {
            db = 0
        } else {
            db = strings.IndexByte(alphabet, b[len(b)+i]) + 1 - zdx
        }
        digit = da - db - carry + zdx
        carry = 0
        if digit <= 0 {
            carry = 1
        }
        a = changeByte(a, i+len(a), alphabet[digit+carry*base-1])
        if i < -len(b) && carry == 0 {
            break
        }
    }
    if carry != 0 {
        log.Fatal("carry should be zero")
    }
    if adt != 0 {
        gi := gIndex(-adt+1, len(a))
        a = insertByte(a, gi, '.')
    }
    a = bTrim(a)
    if bNegate {
        a = negate(a, alphabet)
    }
    return a
}

func bMul(a, b, alphabet string) string {
    zdx := strings.IndexByte(alphabet, '0') + 1
    dpa := strings.IndexByte(a, '.') + 1
    dpb := strings.IndexByte(b, '.') + 1
    ndp := 0
    if dpa != 0 {
        ndp += len(a) - dpa
        a = removeByte(a, dpa-1)
    }
    if dpb != 0 {
        ndp += len(b) - dpb
        b = removeByte(b, dpb-1)
    }
    pos, res := a, "0"
    if zdx != 1 {
        // balanced number systems
        neg := negate(pos, alphabet)
        for i := len(b); i >= 1; i-- {
            m := strings.IndexByte(alphabet, b[i-1]) + 1 - zdx
            for m != 0 {
                temp, temp2 := pos, -1
                if m < 0 {
                    temp = neg
                    temp2 = 1
                }
                res = bAdd(res, temp, alphabet)
                m += temp2
            }
            pos += "0"
            neg += "0"
        }
    } else {
        // non-balanced number systems
        negative := false
        if a[0] == '-' {
            a = a[1:]
            negative = true
        }
        if b[0] == '-' {
            b = b[1:]
            negative = !negative
        }
        for i := len(b); i >= 1; i-- {
            m := strings.IndexByte(alphabet, b[i-1]) + 1 - zdx
            for m > 0 {
                res = bAdd(res, pos, alphabet)
                m--
            }
            pos += "0"
        }
        if negative {
            res = negate(res, alphabet)
        }
    }
    if ndp != 0 {
        gi := gIndex(-ndp, len(res))
        res = insertByte(res, gi, '.')
    }
    res = bTrim(res)
    return res
}

func multTable() {
    fmt.Println("multiplication table")
    fmt.Println("====================")
    fmt.Printf("* |")
    for j := 1; j <= 12; j++ {
        fj := float64(j)
        fmt.Printf(" #%s %3s |", float2b(fj, hexadecimal), float2b(fj, balancedTernary))
    }
    for i := 1; i <= 27; i++ {
        fi := float64(i)
        a := float2b(fi, balancedTernary)
        fmt.Printf("\n%-2s|", float2b(fi, septemVigesimal))
        for j := 1; j <= 12; j++ {
            if j > i {
                fmt.Printf("        |")
            } else {
                fj := float64(j)
                b := float2b(fj, balancedTernary)
                m := bMul(a, b, balancedTernary)
                fmt.Printf(" %6s |", m)
            }
        }
    }
    fmt.Println()
}

func test(name, alphabet string) {
    a := b2b("+-0++0+.+-0++0+", balancedTernary, alphabet)
    b := b2b("-436.436", decimal, alphabet)
    c := b2b("+-++-.+-++-", balancedTernary, alphabet)
    d := bSub(b, c, alphabet)
    r := bMul(a, d, alphabet)
    fmt.Printf("%s\n%s\n", name, strings.Repeat("=", len(name)))
    fmt.Printf("      a = %.16g  %s\n", b2dec(a, alphabet), a)
    fmt.Printf("      b = %.16g  %s\n", b2dec(b, alphabet), b)
    fmt.Printf("      c = %.16g  %s\n", b2dec(c, alphabet), c)
    fmt.Printf("a*(b-c) = %.16g  %s\n\n", b2dec(r, alphabet), r)
}

func main() {
    test("balanced ternary", balancedTernary)
    test("balanced base 27", balancedBase27)
    test("decimal", decimal)
    test("binary", binary)
    test("ternary", ternary)
    test("hexadecimal", hexadecimal)
    test("septemvigesimal", septemVigesimal)
    multTable()
}</syntaxhighlight>

{{out}}
<pre>
balanced ternary
================
      a = 523.2391403749428  +-0++0+.+-0++0+
      b = -436.4359999999999  -++-0--.--0+-00+++-0-+---0-+0++++0--0000+00-+-+--+0-0-00--++0-+00---+0+-+++0+-0----0++
      c = 65.26748971193416  +-++-.+-++-
a*(b-c) = -262510.9026799813  ----000-0+0+.0+0-0-00---00--0-0+--+--00-0++-000++0-000-+0+-----+++-+-0+-+0+0++0+0-++-++0+---00++++

balanced base 27
================
      a = 523.2391403749428  AUJ.FLI
      b = -436.4359999999999  NKQ.YFDFTYSMHVANGXPVXHIZJRJWZD0PBGFJAEBAKOZODLY0ITEHPQLSQSGLFZUINATKCIKUVMWEWJMQ0COTS
      c = 65.26748971193416  BK.GF
a*(b-c) = -262510.9026799812  ZVPJ.CWNYQPEENDVDPNJZXKFGCLHKLCX0YIBOMETHFWWBTVUFAH0SEZMTBJDCRRAQIQCAWMKXSTPYUXYPK0LODUO

decimal
=======
      a = 523.2391403749428  523.239140374942844078646547782350251486053955189757658893461362597165066300868770004
      b = -436.436  -436.436
      c = 65.26748971193413  65.267489711934156378600823045267489711934156378600823045267489711934156378600823045
a*(b-c) = -262510.9026799813  -262510.90267998140903693918986303277315826215892262734715612833785876513103053772667101895163734826631742752252837097627017862754285047634638652268078676654605120794218

binary
======
      a = 523.2391403749427  1000001011.001111010011100001001101101110011000100001011110100101001010100100000111001000111
      b = -436.436  -110110100.011011111001110110110010001011010000111001010110000001000001100010010011011101001
      c = 65.26748971193416  1000001.01000100011110100011010010101100110001100000111010111111101111001001001101111101
a*(b-c) = -262510.9026799814  -1000000000101101110.111001110001011000001001000001101110011111011100000100000100001000101011100011110010110001010100110111001011101001010000001110110100111110001101000000001111110101

ternary
=======
      a = 523.2391403749428  201101.0201101
      b = -436.4360000000002  -121011.102202211210021110012111201022222000202102010100101200200110122011122101110212
      c = 65.26748971193416  2102.02102
a*(b-c) = -262510.9026799813  -111100002121.2201010011100110022102110002120222120100001221111011202022012121122001201122110221112

hexadecimal
===========
      a = 523.2391403749427  20B.3D384DB9885E94A90723EF9CBCB174B443E45FFC41152FE0293416F15E3AC303A0F3799ED81589C62
      b = -436.436  -1B4.6F9DB22D0E5604189374BC6A7EF9DB22D0E5604189374BC6A7EF9DB22D0E5604189374BC6A7EF9DB2
      c = 65.26748971193416  41.447A34ACC60EBFBC937D5DC2E5A99CF8A021B641511E8D2B3183AFEF24DF5770B96A673E28086D905
a*(b-c) = -262510.9026799814  -4016E.E7160906E7DC10422DA508321819F4A637E5AEE668ED5163B12FCB17A732442F589975B7F24112B2E8F6E95EAD45803915EE26D20DF323D67CAEEC75D7BED68AA34E02F2B492257D66F028545FB398F60E

septemvigesimal
===============
      a = 523.2391403749428  JA.6C9
      b = -436.4359999999999  -G4.BKML7C5DJ8Q0KB39AIICH4HACN02OJKGPLOPG2D1MFBQI6LJ33F645JELD7I0Q6FNHG88E9M9GE3QO276
      c = 65.26748971193416  2B.76
a*(b-c) = -262510.9026799812  -D92G.OA1C42LM0N8N30HDAFKJNEIFEOB0BHP1DM6ILA9P797KPJ05MCE6OGMO54Q3I3NQ9DGB673C8BC2FQF1N82

multiplication table
====================
* | #1   + | #2  +- | #3  +0 | #4  ++ | #5 +-- | #6 +-0 | #7 +-+ | #8 +0- | #9 +00 | #A +0+ | #B ++- | #C ++0 |
1 |      + |        |        |        |        |        |        |        |        |        |        |        |
2 |     +- |     ++ |        |        |        |        |        |        |        |        |        |        |
3 |     +0 |    +-0 |    +00 |        |        |        |        |        |        |        |        |        |
4 |     ++ |    +0- |    ++0 |   +--+ |        |        |        |        |        |        |        |        |
5 |    +-- |    +0+ |   +--0 |   +-+- |   +0-+ |        |        |        |        |        |        |        |
6 |    +-0 |    ++0 |   +-00 |   +0-0 |   +0+0 |   ++00 |        |        |        |        |        |        |
7 |    +-+ |   +--- |   +-+0 |   +00+ |   ++0- |  +---0 |  +--++ |        |        |        |        |        |
8 |    +0- |   +--+ |   +0-0 |   ++-- |   ++++ |  +--+0 |  +-0+- |  +-+0+ |        |        |        |        |
9 |    +00 |   +-00 |   +000 |   ++00 |  +--00 |  +-000 |  +-+00 |  +0-00 |  +0000 |        |        |        |
A |    +0+ |   +-+- |   +0+0 |   ++++ |  +-0-- |  +-+-0 |  +0--+ |  +000- |  +0+00 |  ++-0+ |        |        |
B |    ++- |   +-++ |   ++-0 |  +--0- |  +-00+ |  +-++0 |  +00-- |  +0+-+ |  ++-00 |  ++0+- |  +++++ |        |
C |    ++0 |   +0-0 |   ++00 |  +--+0 |  +-+-0 |  +0-00 |  +00+0 |  ++--0 |  ++000 |  ++++0 | +--0-0 | +--+00 |
D |    +++ |   +00- |   +++0 |  +-0-+ |  +-++- |  +00-0 |  +0+0+ |  ++0-- |  +++00 | +---++ | +--+0- | +-0-+0 |
E |   +--- |   +00+ |  +---0 |  +-0+- |  +0--+ |  +00+0 |  ++-0- |  ++0++ | +---00 | +--+-- | +-0-0+ | +-0+-0 |
F |   +--0 |   +0+0 |  +--00 |  +-+-0 |  +0-+0 |  +0+00 |  ++0-0 |  ++++0 | +--000 | +-0--0 | +-00+0 | +-+-00 |
G |   +--+ |   ++-- |  +--+0 |  +-+0+ |  +000- |  ++--0 |  ++0++ | +---+- | +--+00 | +-00-+ | +-+--- | +-+0+0 |
H |   +-0- |   ++-+ |  +-0-0 |  +0--- |  +00++ |  ++-+0 |  ++++- | +--00+ | +-0-00 | +-0+0- | +-+0-+ | +0---0 |
I |   +-00 |   ++00 |  +-000 |  +0-00 |  +0+00 |  ++000 | +---00 | +--+00 | +-0000 | +-+-00 | +-++00 | +0-000 |
J |   +-0+ |   +++- |  +-0+0 |  +0-++ |  ++--- |  +++-0 | +--0-+ | +-0-0- | +-0+00 | +-+00+ | +0--+- | +0-++0 |
K |   +-+- |   ++++ |  +-+-0 |  +000- |  ++-0+ |  ++++0 | +--+-- | +-00-+ | +-+-00 | +-+++- | +0-0++ | +000-0 |
L |   +-+0 |  +---0 |  +-+00 |  +00+0 |  ++0-0 | +---00 | +--++0 | +-0+-0 | +-+000 | +0--+0 | +00--0 | +00+00 |
M |   +-++ |  +--0- |  +-++0 |  +0+-+ |  ++0+- | +--0-0 | +-0-0+ | +-+--- | +-++00 | +0-0++ | +0000- | +0+-+0 |
N |   +0-- |  +--0+ |  +0--0 |  +0++- |  +++-+ | +--0+0 | +-000- | +-+-++ | +0--00 | +00--- | +00+0+ | +0++-0 |
O |   +0-0 |  +--+0 |  +0-00 |  ++--0 |  ++++0 | +--+00 | +-0+-0 | +-+0+0 | +0-000 | +000-0 | +0+-+0 | ++--00 |
P |   +0-+ |  +-0-- |  +0-+0 |  ++-0+ | +---0- | +-0--0 | +-0+++ | +-+++- | +0-+00 | +00+-+ | +0++-- | ++-0+0 |
Q |   +00- |  +-0-+ |  +00-0 |  ++0-- | +---++ | +-0-+0 | +-+-+- | +0--0+ | +00-00 | +0+-0- | ++---+ | ++0--0 |
10|   +000 |  +-000 |  +0000 |  ++000 | +--000 | +-0000 | +-+000 | +0-000 | +00000 | +0+000 | ++-000 | ++0000 |
</pre>


=={{header|Julia}}==
<syntaxhighlight lang="julia">using Formatting
import Base.BigInt, Base.BigFloat, Base.print, Base.+, Base.-, Base.*

abstract type BalancedBaseDigitArray end

mutable struct BalancedTernary <: BalancedBaseDigitArray
    dig::Vector{Int8}
    p::Int
    BalancedTernary(arr::Vector, i) = new(Int8.(arr), i)
end

const MAX_PRECISION = 81

function BalancedTernary(s::String)
    if (i = findfirst(x -> x == '.', s)) != nothing
        p = length(s) - i
        s = s[1:i-1] * s[i+1:end]
    else
        p = 0
    end
    b = BalancedTernary([c == '-' ? -1 : c == '0' ? 0 : 1 for c in s], p)  # 2
end

function BalancedTernary(n::Integer)                                                # 1, 3
    if n < 0
        return -BalancedTernary(-n)
    elseif n == 0
        return BalancedTernary([0], 0)
    else
        return canonicalize!(BalancedTernary(reverse(digits(n, base=3)), 0))
    end
end
BalancedTernary() = BalancedTernary(0)

function BalancedTernary(x::Real)                                             # 1, 3
    if x < 0
        return -BalancedTernary(-x)
    end
    arr = reverse(digits(BigInt(round(x * big"3.0"^MAX_PRECISION)), base=3))
    return canonicalize!(BalancedTernary(arr, MAX_PRECISION))
end

function String(b::BalancedTernary)                                           # 3
    canonicalize!(b)
    s = String([['-', '0', '+'][c + 2] for c in b.dig])
    if b.p > 0
        if b.p < length(s)
            s = s[1:end-b.p] * "." * s[end-b.p+1:end]
        elseif b.p == length(s)
            s = "0." * s
        else
            s = "0." * "0"^(b.p - length(s)) * s
        end
    end
    return s
end

function BigInt(b::BalancedTernary)
    canonicalize!(b)
    if b.p > 0
        throw(InexactError("$(b.p) places after decimal point"))
    end
    return sum(t -> BigInt(3)^(t[1] - 1) * t[2], enumerate(reverse(b.dig)))          # 3
end

BigFloat(b::BalancedTernary) = BigInt(BalancedTernary(b.dig, 0)) / big"3.0"^(b.p)

function canonicalize!(b::BalancedTernary)
    for i in length(b.dig):-1:1
        if b.dig[i] > 1
            b.dig[i] -= 3
            if i == 1
                pushfirst!(b.dig, 1)
            else
                b.dig[i - 1] += 1
            end
        elseif b.dig[i] < -1
            b.dig[i] += 3
            if i == 1
                pushfirst!(b.dig, -1)
            else
                b.dig[i - 1] -= 1
            end
        end
    end
    if (i = findfirst(x -> x != 0, b.dig)) != nothing
        if i > 1
            b.dig = b.dig[i:end]
        end
    else
        b.dig = [0]
    end
    if b.p > 0 && (i = findlast(x -> x != 0, b.dig)) != nothing
        removable = min(b.p, length(b.dig) - i)
        b.dig = b.dig[1:end-removable]
        b.p -= removable
    end
    return b
end

# The following should work with any base number where dig, p are a similar array and Int
# and the proper constructors, canon, and conversion routines are defined     # 6

Base.print(io::IO, b::BalancedBaseDigitArray) = print(io, String(b))

function +(b1::T, b2::T) where T <: BalancedBaseDigitArray                 # 4
    if all(x -> x == 0, b1.dig)
        return deepcopy(b2)
    elseif all(x -> x == 0, b2.dig)
        return deepcopy(b1)
    end
    ldigits1 = length(b1.dig) - b1.p
    arr = b1.dig[1:ldigits1]
    ldigits2 = length(b2.dig) - b2.p
    arr2 = b2.dig[1:ldigits2]
    if (i = ldigits1 - ldigits2) > 0
        arr2 = [zeros(Int8, i); arr2]
    elseif i < 0
        arr = [zeros(Int8, -i); arr]
    end
    if (i = b1.p - b2.p) > 0
        arr = [arr; b1.dig[ldigits1+1:end]]
        arr2 = [arr2; b2.dig[ldigits2+1:end]; zeros(Int8, i)]
    elseif i < 0
        arr = [arr; b1.dig[ldigits1+1:end]; zeros(Int8, -i)]
        arr2 = [arr2; b2.dig[ldigits2+1:end]]
    else
        arr = [arr; b1.dig[ldigits1+1:end]]
        arr2 = [arr2; b2.dig[ldigits2+1:end]]
    end
    arr .+= arr2
    return canonicalize!(T(arr, max(b1.p, b2.p)))
end

-(b1::T) where T <: BalancedBaseDigitArray = T(b1.dig .* -1, b1.p)            # 4
-(b1::T, b2::T) where T <: BalancedBaseDigitArray = +(b1, -b2)                # 4

function *(b1::T, b2::T) where T <: BalancedBaseDigitArray                    # 4
    len = length(b2.dig)
    bsum = T()
    for i in len:-1:1
        bsum += T([b1.dig .* b2.dig[i]; zeros(Int8, len - i)], 0)
    end
    bsum.p = b1.p + b2.p
    return canonicalize!(bsum)
end

function code_reuse_task(T::Type)
    a = T("+-0++0+.+-0++0+")
    b = T(-436.436)
    c = T("+-++-.+-++-")
    println(" a = ", a, " = ", format(BigFloat(a)))
    println(" b = ", b, " = ", format(BigFloat(b)))
    println(" c = ", c, " = ", format(BigFloat(c)))
    println("\na * (b - c) = ", String(a * (b - c)), "\n = ", format(BigFloat(a * (b - c))))

    println("\n           Multiplication 27 X 12")
    println(" x|+ (1)  |+- (2) |+0 (3) |++ (4) |+-- (5)|+-0 (6)|+-+ (7)|+0- (8)|+e+-(9)|+0+(10)|++-(11)|++0(12)|")
    for i in 1:27
        print(lpad(i, 2), "|")
        for j in 1:12
            print(lpad(String(T(i * j)), 7), "|")
        end
        print("\n")
    end
end

code_reuse_task(BalancedTernary)
</syntaxhighlight>{{out}}
<pre>
 a = +-0++0+.+-0++0+ = 523.23914
 b = -++-0--.--0+-00+++-0-+---0-+0++++0--++++0-+0+-0+0+-000-0----+0--0---+-000++--++-+-0--0-+ = -436.436
 c = +-++-.+-++- = 65.26749

a * (b - c) = ----000-0+0+.0+0-0-00---00--0-0+--+0-0+0++-+-0--0--+0-++-0-+00-++0-0-0+++--0-+0--+-++-+-+-++-+0+-+-+
 = -262510.90268

           Multiplication 27 X 12
 x|+ (1)  |+- (2) |+0 (3) |++ (4) |+-- (5)|+-0 (6)|+-+ (7)|+0- (8)|+e+-(9)|+0+(10)|++-(11)|++0(12)|
 1|      +|     +-|     +0|     ++|    +--|    +-0|    +-+|    +0-|    +00|    +0+|    ++-|    ++0|
 2|     +-|     ++|    +-0|    +0-|    +0+|    ++0|   +---|   +--+|   +-00|   +-+-|   +-++|   +0-0|
 3|     +0|    +-0|    +00|    ++0|   +--0|   +-00|   +-+0|   +0-0|   +000|   +0+0|   ++-0|   ++00|
 4|     ++|    +0-|    ++0|   +--+|   +-+-|   +0-0|   +00+|   ++--|   ++00|   ++++|  +--0-|  +--+0|
 5|    +--|    +0+|   +--0|   +-+-|   +0-+|   +0+0|   ++0-|   ++++|  +--00|  +-0--|  +-00+|  +-+-0|
 6|    +-0|    ++0|   +-00|   +0-0|   +0+0|   ++00|  +---0|  +--+0|  +-000|  +-+-0|  +-++0|  +0-00|
 7|    +-+|   +---|   +-+0|   +00+|   ++0-|  +---0|  +--++|  +-0+-|  +-+00|  +0--+|  +00--|  +00+0|
 8|    +0-|   +--+|   +0-0|   ++--|   ++++|  +--+0|  +-0+-|  +-+0+|  +0-00|  +000-|  +0+-+|  ++--0|
 9|    +00|   +-00|   +000|   ++00|  +--00|  +-000|  +-+00|  +0-00|  +0000|  +0+00|  ++-00|  ++000|
10|    +0+|   +-+-|   +0+0|   ++++|  +-0--|  +-+-0|  +0--+|  +000-|  +0+00|  ++-0+|  ++0+-|  ++++0|
11|    ++-|   +-++|   ++-0|  +--0-|  +-00+|  +-++0|  +00--|  +0+-+|  ++-00|  ++0+-|  +++++| +--0-0|
12|    ++0|   +0-0|   ++00|  +--+0|  +-+-0|  +0-00|  +00+0|  ++--0|  ++000|  ++++0| +--0-0| +--+00|
13|    +++|   +00-|   +++0|  +-0-+|  +-++-|  +00-0|  +0+0+|  ++0--|  +++00| +---++| +--+0-| +-0-+0|
14|   +---|   +00+|  +---0|  +-0+-|  +0--+|  +00+0|  ++-0-|  ++0++| +---00| +--+--| +-0-0+| +-0+-0|
15|   +--0|   +0+0|  +--00|  +-+-0|  +0-+0|  +0+00|  ++0-0|  ++++0| +--000| +-0--0| +-00+0| +-+-00|
16|   +--+|   ++--|  +--+0|  +-+0+|  +000-|  ++--0|  ++0++| +---+-| +--+00| +-00-+| +-+---| +-+0+0|
17|   +-0-|   ++-+|  +-0-0|  +0---|  +00++|  ++-+0|  ++++-| +--00+| +-0-00| +-0+0-| +-+0-+| +0---0|
18|   +-00|   ++00|  +-000|  +0-00|  +0+00|  ++000| +---00| +--+00| +-0000| +-+-00| +-++00| +0-000|
19|   +-0+|   +++-|  +-0+0|  +0-++|  ++---|  +++-0| +--0-+| +-0-0-| +-0+00| +-+00+| +0--+-| +0-++0|
20|   +-+-|   ++++|  +-+-0|  +000-|  ++-0+|  ++++0| +--+--| +-00-+| +-+-00| +-+++-| +0-0++| +000-0|
21|   +-+0|  +---0|  +-+00|  +00+0|  ++0-0| +---00| +--++0| +-0+-0| +-+000| +0--+0| +00--0| +00+00|
22|   +-++|  +--0-|  +-++0|  +0+-+|  ++0+-| +--0-0| +-0-0+| +-+---| +-++00| +0-0++| +0000-| +0+-+0|
23|   +0--|  +--0+|  +0--0|  +0++-|  +++-+| +--0+0| +-000-| +-+-++| +0--00| +00---| +00+0+| +0++-0|
24|   +0-0|  +--+0|  +0-00|  ++--0|  ++++0| +--+00| +-0+-0| +-+0+0| +0-000| +000-0| +0+-+0| ++--00|
25|   +0-+|  +-0--|  +0-+0|  ++-0+| +---0-| +-0--0| +-0+++| +-+++-| +0-+00| +00+-+| +0++--| ++-0+0|
26|   +00-|  +-0-+|  +00-0|  ++0--| +---++| +-0-+0| +-+-+-| +0--0+| +00-00| +0+-0-| ++---+| ++0--0|
27|   +000|  +-000|  +0000|  ++000| +--000| +-0000| +-+000| +0-000| +00000| +0+000| ++-000| ++0000|
</pre>

=={{header|Phix}}==
Note regarding requirement #5: While this meets my definition of "reasonably efficient", 
it should not shock anyone that this kind of "string maths" which works digit-by-digit 
and uses repeated addition (eg *999 performs 27 additions) could easily be 10,000 times 
slower than raw hardware or a carefully optimised library such as gmp. However this does
offer perfect accuracy in any given base, whereas gmp, for all it's brilliance, can hold 
0.1 accurate to several million decimal places, but just never quite exact.

<!--<syntaxhighlight lang="phix">(phixonline)-->
 <span style="color: #000080;font-style:italic;">-- demo\rosetta\Generic_multiplication.exw</span>
 <span style="color: #008080;">constant</span> <span style="color: #000000;">MAX_DP</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">81</span>
  
 <span style="color: #008080;">constant</span> <span style="color: #000000;">binary</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"01"</span><span style="color: #0000FF;">,</span>
          <span style="color: #000000;">ternary</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"012"</span><span style="color: #0000FF;">,</span>
          <span style="color: #000000;">balancedternary</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"-0+"</span><span style="color: #0000FF;">,</span>
          <span style="color: #000000;">decimal</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"0123456789"</span><span style="color: #0000FF;">,</span>
          <span style="color: #000000;">hexadecimal</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"0123456789ABCDEF"</span><span style="color: #0000FF;">,</span>
          <span style="color: #000000;">septemvigesimal</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"0123456789ABCDEFGHIJKLMNOPQ"</span><span style="color: #0000FF;">,</span>
 <span style="color: #000080;font-style:italic;">--       heptavintimal   = "0123456789ABCDEFGHKMNPRTVXZ", -- ??
 --       wonky_donkey_26 = "0ABCDEFGHIJKLMNOPQRSTUVWXY",
 --       wonky_donkey_27 = "0ABCDEFGHIJKLMNOPQRSTUVWXYZ",</span>
          <span style="color: #000000;">balanced_base27</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"ZYXWVUTSRQPON0ABCDEFGHIJKLM"</span><span style="color: #0000FF;">,</span>
          <span style="color: #000000;">base37</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"</span>
 <span style="color: #000080;font-style:italic;">--
 --Note: I have seen some schemes where balanced-base-27 uses
 --====  the same character set as septemvigesimal, with 'D'
 --      representing 0, and wonky_donkey_27 with 'M'==0(!).
 --      These routines do not support that directly, except 
 --      (perhaps) via a simple mapping on all inputs/outputs.
 --      It may be possible to add a defaulted parameter such 
 --      as zero='0' - left as an exercise for the reader.
 --      Admittedly that balanced_base27 is entirely my own
 --      invention, just for this specific task.
 --</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">b2dec</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
 <span style="color: #000080;font-style:italic;">--
 -- convert string b back into a normal (decimal) atom,
 --  eg b2dec("+0-",balancedternary) yields 8
 --</span>
     <span style="color: #004080;">atom</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">base</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">zdx</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
     <span style="color: #004080;">bool</span> <span style="color: #000000;">signed</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">(</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">and</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">signed</span> <span style="color: #008080;">then</span> <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$]</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">len</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">ndp</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">ndp</span><span style="color: #0000FF;">..</span><span style="color: #000000;">ndp</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> <span style="color: #000080;font-style:italic;">-- remove '.'</span>
         <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">len</span><span style="color: #0000FF;">-</span><span style="color: #000000;">ndp</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
         <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">base</span><span style="color: #0000FF;">*</span><span style="color: #000000;">res</span><span style="color: #0000FF;">+</span><span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">ndp</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">/=</span> <span style="color: #7060A8;">power</span><span style="color: #0000FF;">(</span><span style="color: #000000;">base</span><span style="color: #0000FF;">,</span><span style="color: #000000;">ndp</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">signed</span> <span style="color: #008080;">then</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">res</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">return</span> <span style="color: #000000;">res</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
 <span style="color: #000080;font-style:italic;">--
 -- negate b (can be balanced or unbalanced)
 --</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'0'</span> <span style="color: #008080;">then</span>
         <span style="color: #000080;font-style:italic;">-- traditional: add/remove a leading '-'
         -- eg "-123" &lt;==&gt; "123"</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">!=</span><span style="color: #008000;">"0"</span> <span style="color: #008080;">then</span>
             <span style="color: #008080;">if</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span> <span style="color: #008080;">then</span>
                 <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$]</span>
             <span style="color: #008080;">else</span>
                 <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"-"</span><span style="color: #0000FF;">&</span><span style="color: #000000;">b</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">else</span>
         <span style="color: #000080;font-style:italic;">-- balanced: mirror [non-0] digits
         -- eg "-0+" (ie -8) &lt;==&gt; "+0-" (ie +8)</span>
         <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
             <span style="color: #008080;">if</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]!=</span><span style="color: #008000;">'.'</span> <span style="color: #008080;">then</span>
                 <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[-</span><span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)]</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">return</span> <span style="color: #000000;">b</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">b_trim</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">)</span>
 <span style="color: #000080;font-style:italic;">-- (common code)
     -- trim trailing ".000"</span>
     <span style="color: #008080;">if</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">trim_tail</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">trim_tail</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">),</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #000080;font-style:italic;">-- trim leading zeroes, but not "0.nnn" -&gt; ".nnn"
     -- [hence we cannot use the standard trim_head()]</span>
     <span style="color: #008080;">while</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)></span><span style="color: #000000;">1</span> <span style="color: #008080;">and</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'0'</span> <span style="color: #008080;">and</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">]!=</span><span style="color: #008000;">'.'</span> <span style="color: #008080;">do</span>
         <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$]</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
     <span style="color: #008080;">return</span> <span style="color: #000000;">b</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">b_carry</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">digit</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">base</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">idx</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">string</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
 <span style="color: #000080;font-style:italic;">-- (common code, for balanced number systems only)</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">></span><span style="color: #000000;">base</span><span style="color: #0000FF;">?+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">digit</span><span style="color: #0000FF;"><</span><span style="color: #000000;">1</span><span style="color: #0000FF;">?-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #000000;">0</span><span style="color: #0000FF;">))</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">carry</span> <span style="color: #008080;">then</span>
         <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">idx</span> <span style="color: #008080;">to</span> <span style="color: #000000;">0</span> <span style="color: #008080;">by</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
             <span style="color: #008080;">if</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]!=</span><span style="color: #008000;">'.'</span> <span style="color: #008080;">then</span>
                 <span style="color: #004080;">integer</span> <span style="color: #000000;">k</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
                 <span style="color: #008080;">if</span> <span style="color: #000000;">k</span><span style="color: #0000FF;"><</span><span style="color: #000000;">base</span> <span style="color: #008080;">then</span>
                     <span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">k</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span>
                     <span style="color: #008080;">exit</span>
                 <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
                 <span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]=</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
         <span style="color: #000000;">digit</span> <span style="color: #0000FF;">-=</span> <span style="color: #000000;">base</span><span style="color: #0000FF;">*</span><span style="color: #000000;">carry</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">return</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">}</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">b2b</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet2</span><span style="color: #0000FF;">)</span>
 <span style="color: #000080;font-style:italic;">--
 -- convert a string from alphabet to alphabet2, 
 --  eg b2b("8",decimal,balancedternary) yields "+0-",
 --   & b2b("+0-",balancedternary,decimal) yields "8",
 --</span>
     <span style="color: #004080;">string</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"0"</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">m</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">!=</span><span style="color: #008000;">"0"</span> <span style="color: #008080;">then</span>
         <span style="color: #004080;">integer</span> <span style="color: #000000;">base</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
                 <span style="color: #000000;">base2</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">alphabet2</span><span style="color: #0000FF;">),</span>
                 <span style="color: #000000;">zdx</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
                 <span style="color: #000000;">zdx2</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet2</span><span style="color: #0000FF;">),</span>
                 <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">q</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">r</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">digit</span>
         <span style="color: #004080;">bool</span> <span style="color: #000000;">negative</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">((</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">and</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">or</span>
                          <span style="color: #0000FF;">(</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">1</span> <span style="color: #008080;">and</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)<</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">))</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">negative</span> <span style="color: #008080;">then</span> <span style="color: #000000;">n</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #004080;">integer</span> <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">ndp</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span>
             <span style="color: #0000FF;">{</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #000000;">m</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">ndp</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">],</span><span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">ndp</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..$]}</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span>
         <span style="color: #008080;">while</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
             <span style="color: #000000;">q</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
             <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
                 <span style="color: #000080;font-style:italic;">--
                 -- this is a digit-by-digit divide (/mod) loop
                 -- eg for hex-&gt;decimal we would want:
                 --  this loop/modrem("FFFF",10) --&gt; "1999" rem 5,
                 --  this loop/modrem("1999",10) --&gt; "28F" rem 3,
                 --  this loop/modrem("28F",10) --&gt; "41" rem 5,
                 --  this loop/modrem("41",10) --&gt; "6" rem 5,
                 --  this loop/modrem("6",10) --&gt; "0" rem 6,
                 -- ==&gt; res:="65535" (in 5 full iterations over n).
                 --</span>
                 <span style="color: #000000;">digit</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span>
                 <span style="color: #000000;">q</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">q</span><span style="color: #0000FF;">*</span><span style="color: #000000;">base</span><span style="color: #0000FF;">+</span><span style="color: #000000;">digit</span>
                 <span style="color: #000000;">r</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">mod</span><span style="color: #0000FF;">(</span><span style="color: #000000;">q</span><span style="color: #0000FF;">,</span><span style="color: #000000;">base2</span><span style="color: #0000FF;">)</span>
                 <span style="color: #000000;">digit</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">floor</span><span style="color: #0000FF;">(</span><span style="color: #000000;">q</span><span style="color: #0000FF;">/</span><span style="color: #000000;">base2</span><span style="color: #0000FF;">)+</span><span style="color: #000000;">zdx</span>
                 <span style="color: #008080;">if</span> <span style="color: #000000;">zdx</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
                     <span style="color: #0000FF;">{</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_carry</span><span style="color: #0000FF;">(</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">,</span><span style="color: #000000;">base</span><span style="color: #0000FF;">,</span><span style="color: #000000;">i</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
                 <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
                 <span style="color: #000000;">n</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">]</span>
                 <span style="color: #000000;">q</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">r</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
             <span style="color: #000000;">r</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">zdx2</span>
             <span style="color: #008080;">if</span> <span style="color: #000000;">zdx2</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
                 <span style="color: #000000;">r</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">carry</span>
                 <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">r</span><span style="color: #0000FF;">></span><span style="color: #000000;">base2</span><span style="color: #0000FF;">?+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">r</span><span style="color: #0000FF;"><</span><span style="color: #000000;">1</span><span style="color: #0000FF;">?-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #000000;">0</span><span style="color: #0000FF;">))</span>
                 <span style="color: #000000;">r</span> <span style="color: #0000FF;">-=</span> <span style="color: #000000;">base2</span><span style="color: #0000FF;">*</span><span style="color: #000000;">carry</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
             <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet2</span><span style="color: #0000FF;">[</span><span style="color: #000000;">r</span><span style="color: #0000FF;">]&</span><span style="color: #000000;">res</span>
             <span style="color: #000000;">n</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">trim_head</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">carry</span> <span style="color: #008080;">then</span>
             <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet2</span><span style="color: #0000FF;">[</span><span style="color: #000000;">carry</span><span style="color: #0000FF;">+</span><span style="color: #000000;">zdx2</span><span style="color: #0000FF;">]&</span><span style="color: #000000;">res</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">if</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span>
             <span style="color: #000000;">res</span> <span style="color: #0000FF;">&=</span> <span style="color: #008000;">'.'</span>
             <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
             <span style="color: #008080;">if</span> <span style="color: #000000;">zdx</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
                 <span style="color: #000080;font-style:italic;">-- convert fraction to unbalanced, to simplify the (other-base) multiply.</span>
                 <span style="color: #004080;">integer</span> <span style="color: #000000;">lm</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">)</span>
                 <span style="color: #004080;">string</span> <span style="color: #000000;">alphanew</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">base37</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)]</span>
                 <span style="color: #000000;">m</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b2b</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphanew</span><span style="color: #0000FF;">)</span> <span style="color: #000080;font-style:italic;">-- (nb: no fractional part!)</span>
                 <span style="color: #000000;">m</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">lm</span><span style="color: #0000FF;">-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">))&</span><span style="color: #000000;">m</span> <span style="color: #000080;font-style:italic;">-- zero-pad if required</span>
                 <span style="color: #000000;">alphabet</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphanew</span>
                 <span style="color: #000000;">zdx</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
             <span style="color: #008080;">while</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">and</span> <span style="color: #000000;">ndp</span><span style="color: #0000FF;"><</span><span style="color: #000000;">MAX_DP</span> <span style="color: #008080;">do</span>
                 <span style="color: #000000;">q</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
                 <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">to</span> <span style="color: #000000;">1</span> <span style="color: #008080;">by</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
                     <span style="color: #000080;font-style:italic;">--
                     -- this is a digit-by-digit multiply loop
                     -- eg for [.]"1415" decimal-&gt;decimal we
                     -- would repeatedly multiply by 10, giving 
                     -- 1 and "4150", then 4 and "1500", then
                     -- 1 and "5000", then 5 and "0000". We
                     -- strip zeroes between each output digit
                     -- & obviously normally alphabet in!=out.
                     --</span>
                     <span style="color: #000000;">digit</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span>
                     <span style="color: #000000;">q</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">digit</span><span style="color: #0000FF;">*</span><span style="color: #000000;">base2</span>
                     <span style="color: #000000;">r</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">mod</span><span style="color: #0000FF;">(</span><span style="color: #000000;">q</span><span style="color: #0000FF;">,</span><span style="color: #000000;">base</span><span style="color: #0000FF;">)+</span><span style="color: #000000;">zdx</span>
                     <span style="color: #000000;">q</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">floor</span><span style="color: #0000FF;">(</span><span style="color: #000000;">q</span><span style="color: #0000FF;">/</span><span style="color: #000000;">base</span><span style="color: #0000FF;">)</span>
                     <span style="color: #000000;">m</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">r</span><span style="color: #0000FF;">]</span>
                 <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
                 <span style="color: #000000;">digit</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">q</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">zdx2</span>
                 <span style="color: #008080;">if</span> <span style="color: #000000;">zdx2</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
                     <span style="color: #0000FF;">{</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">,</span><span style="color: #000000;">res</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_carry</span><span style="color: #0000FF;">(</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">,</span><span style="color: #000000;">base2</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">),</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet2</span><span style="color: #0000FF;">)</span>
                 <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
                 <span style="color: #000000;">res</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">alphabet2</span><span style="color: #0000FF;">[</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">]</span>
                 <span style="color: #000000;">m</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">trim_tail</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;">,</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">)</span>
                 <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_trim</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">negative</span> <span style="color: #008080;">then</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet2</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">return</span> <span style="color: #000000;">res</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">atm2b</span><span style="color: #0000FF;">(</span><span style="color: #004080;">atom</span> <span style="color: #000000;">d</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">string</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
 <span style="color: #000080;font-style:italic;">--
 -- convert d to a string in the specified base,
 --   eg atm2b(65535,hexadecimal) =&gt; "FFFF"
 --
 -- As a standard feature of phix, you can actually specify 
 -- d in any number base between 2 and 36, eg 0(13)168 is
 -- equivalent to 255 (see test\t37misc.exw for more), but
 -- not (yet) in balanced number bases, or with fractions,
 -- except (of course) for normal decimal fractions.
 --
 -- Note that eg b2b("-436.436",decimal,balancedternary) is 
 -- more acccurate that atm2b(-436.436,balancedternary) due
 -- to standard IEEE 754 floating point limitations.
 -- For integers, discrepancies only creep in for values 
 -- outside the range +/-9,007,199,254,740,992 (on 32-bit).
 -- However, this is much simpler and faster than b2b().
 --</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">base</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">zdx</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
     <span style="color: #004080;">bool</span> <span style="color: #000000;">neg</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">d</span><span style="color: #0000FF;"><</span><span style="color: #000000;">0</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">neg</span> <span style="color: #008080;">then</span> <span style="color: #000000;">d</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">d</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #004080;">string</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">whole</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">floor</span><span style="color: #0000FF;">(</span><span style="color: #000000;">d</span><span style="color: #0000FF;">)</span>
     <span style="color: #000000;">d</span> <span style="color: #0000FF;">-=</span> <span style="color: #000000;">whole</span>
     <span style="color: #008080;">while</span> <span style="color: #004600;">true</span> <span style="color: #008080;">do</span>
         <span style="color: #004080;">integer</span> <span style="color: #000000;">ch</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">mod</span><span style="color: #0000FF;">(</span><span style="color: #000000;">whole</span><span style="color: #0000FF;">,</span><span style="color: #000000;">base</span><span style="color: #0000FF;">)</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">zdx</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">zdx</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
             <span style="color: #000000;">ch</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">carry</span>
             <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">ch</span><span style="color: #0000FF;">></span><span style="color: #000000;">base</span><span style="color: #0000FF;">?+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">ch</span><span style="color: #0000FF;"><</span><span style="color: #000000;">1</span><span style="color: #0000FF;">?-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #000000;">0</span><span style="color: #0000FF;">))</span>
             <span style="color: #000000;">ch</span> <span style="color: #0000FF;">-=</span> <span style="color: #000000;">base</span><span style="color: #0000FF;">*</span><span style="color: #000000;">carry</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">ch</span><span style="color: #0000FF;">]&</span><span style="color: #000000;">res</span>
         <span style="color: #000000;">whole</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">floor</span><span style="color: #0000FF;">(</span><span style="color: #000000;">whole</span><span style="color: #0000FF;">/</span><span style="color: #000000;">base</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">whole</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">carry</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">carry</span><span style="color: #0000FF;">+</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">]&</span><span style="color: #000000;">res</span>
         <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">d</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">res</span> <span style="color: #0000FF;">&=</span> <span style="color: #008000;">'.'</span>
         <span style="color: #004080;">integer</span> <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
         <span style="color: #008080;">while</span> <span style="color: #000000;">d</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">0</span> <span style="color: #008080;">and</span> <span style="color: #000000;">ndp</span><span style="color: #0000FF;"><</span><span style="color: #000000;">MAX_DP</span> <span style="color: #008080;">do</span>
             <span style="color: #000000;">d</span> <span style="color: #0000FF;">*=</span> <span style="color: #000000;">base</span>
             <span style="color: #004080;">integer</span> <span style="color: #000000;">digit</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">floor</span><span style="color: #0000FF;">(</span><span style="color: #000000;">d</span><span style="color: #0000FF;">)</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">zdx</span>
             <span style="color: #000000;">d</span> <span style="color: #0000FF;">-=</span> <span style="color: #000000;">digit</span>
             <span style="color: #008080;">if</span> <span style="color: #000000;">zdx</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
                 <span style="color: #0000FF;">{</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">,</span><span style="color: #000000;">res</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_carry</span><span style="color: #0000FF;">(</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">,</span><span style="color: #000000;">base</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">),</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
             <span style="color: #000000;">res</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">]</span>
             <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">neg</span> <span style="color: #008080;">then</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">return</span> <span style="color: #000000;">res</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #000080;font-style:italic;">-- negative numbers in addition and subtraction 
 -- (esp. non-balanced) are treated as follows:
 -- for -ve a:   (-a)+b == b-a;      (-a)-b == -(a+b)
 -- for -ve b:   a+(-b) == a-b;      a-(-b) == a+b
 -- for a&gt;b:     a-b == -(b-a)  [avoid running off end]</span>
  
 <span style="color: #008080;">forward</span> <span style="color: #008080;">function</span> <span style="color: #000000;">b_sub</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">b_add</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">base</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">zdx</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">da</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">db</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">digit</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">zdx</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span> <span style="color: #008080;">then</span>    <span style="color: #000080;font-style:italic;">-- (-a)+b == b-a</span>
             <span style="color: #008080;">return</span> <span style="color: #000000;">b_sub</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span> <span style="color: #008080;">then</span>    <span style="color: #000080;font-style:italic;">-- a+(-b) == a-b</span>
             <span style="color: #008080;">return</span> <span style="color: #000000;">b_sub</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">adt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">a</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">bdt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">adt</span> <span style="color: #008080;">or</span> <span style="color: #000000;">bdt</span> <span style="color: #008080;">then</span>
         <span style="color: #000080;font-style:italic;">-- remove the '.'s and zero-pad the shorter as needed
         --   (thereafter treat them as two whole integers)
         -- eg "1.23"+"4.5" -&gt; "123"+"450" (leaving adt==2)</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">adt</span> <span style="color: #008080;">then</span> <span style="color: #000000;">adt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">;</span>  <span style="color: #000000;">a</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">..-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">bdt</span> <span style="color: #008080;">then</span> <span style="color: #000000;">bdt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">;</span>  <span style="color: #000000;">b</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">..-</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">bdt</span><span style="color: #0000FF;">></span><span style="color: #000000;">adt</span> <span style="color: #008080;">then</span>
             <span style="color: #000000;">a</span> <span style="color: #0000FF;">&=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">)</span>
             <span style="color: #000000;">adt</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">bdt</span>
         <span style="color: #008080;">elsif</span> <span style="color: #000000;">adt</span><span style="color: #0000FF;">></span><span style="color: #000000;">bdt</span> <span style="color: #008080;">then</span>
             <span style="color: #000000;">b</span> <span style="color: #0000FF;">&=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">-</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">if</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)<</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span>
         <span style="color: #0000FF;">{</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">a</span><span style="color: #0000FF;">}</span>   <span style="color: #000080;font-style:italic;">-- ensure b is the shorter</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=-</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #0000FF;">-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">by</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
         <span style="color: #000000;">da</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;"><-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)?</span><span style="color: #000000;">0</span><span style="color: #0000FF;">:</span><span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">)</span>
         <span style="color: #000000;">db</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;"><-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)?</span><span style="color: #000000;">0</span><span style="color: #0000FF;">:</span><span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">)</span>
         <span style="color: #000000;">digit</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">da</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">db</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">carry</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">zdx</span>
         <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">></span><span style="color: #000000;">base</span><span style="color: #0000FF;">?+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">digit</span><span style="color: #0000FF;"><</span><span style="color: #000000;">1</span><span style="color: #0000FF;">?-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #000000;">0</span><span style="color: #0000FF;">))</span>
         <span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">-</span><span style="color: #000000;">carry</span><span style="color: #0000FF;">*</span><span style="color: #000000;">base</span><span style="color: #0000FF;">]</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">i</span><span style="color: #0000FF;"><-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">and</span> <span style="color: #000000;">carry</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">carry</span> <span style="color: #008080;">then</span> 
         <span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">carry</span><span style="color: #0000FF;">+</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">]&</span><span style="color: #000000;">a</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">adt</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">a</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"."</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_trim</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">return</span> <span style="color: #000000;">a</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">a_smaller</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
 <span style="color: #000080;font-style:italic;">-- return true if a is smaller than b
 -- if not balanced then both are +ve</span>
     <span style="color: #008080;">if</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)!=</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span> <span style="color: #0000FF;">?</span><span style="color: #000000;">9</span><span style="color: #0000FF;">/</span><span style="color: #000000;">0</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span> <span style="color: #000080;font-style:italic;">-- sanity check</span>
     <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
         <span style="color: #004080;">integer</span> <span style="color: #000000;">da</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
                 <span style="color: #000000;">db</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
                 <span style="color: #000000;">c</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">compare</span><span style="color: #0000FF;">(</span><span style="color: #000000;">da</span><span style="color: #0000FF;">,</span><span style="color: #000000;">db</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">c</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">return</span> <span style="color: #000000;">c</span><span style="color: #0000FF;"><</span><span style="color: #000000;">0</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
     <span style="color: #008080;">return</span> <span style="color: #004600;">false</span> <span style="color: #000080;font-style:italic;">-- (=, which is not &lt;)</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">b_sub</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">base</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">zdx</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">da</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">db</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">digit</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">zdx</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span> <span style="color: #008080;">then</span>    <span style="color: #000080;font-style:italic;">-- (-a)-b == -(a+b)</span>
             <span style="color: #008080;">return</span> <span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b_add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span> <span style="color: #008080;">then</span>    <span style="color: #000080;font-style:italic;">-- a-(-b) == a+b</span>
             <span style="color: #008080;">return</span> <span style="color: #000000;">b_add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">adt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">a</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">bdt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">adt</span> <span style="color: #008080;">or</span> <span style="color: #000000;">bdt</span> <span style="color: #008080;">then</span>
         <span style="color: #000080;font-style:italic;">-- remove the '.'s and zero-pad the shorter as needed
         --   (thereafter treat them as two whole integers)
         -- eg "1.23"+"4.5" -&gt; "123"+"450" (leaving adt==2)</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">adt</span> <span style="color: #008080;">then</span> <span style="color: #000000;">adt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">;</span>  <span style="color: #000000;">a</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">..-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">bdt</span> <span style="color: #008080;">then</span> <span style="color: #000000;">bdt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">;</span>  <span style="color: #000000;">b</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">..-</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">bdt</span><span style="color: #0000FF;">></span><span style="color: #000000;">adt</span> <span style="color: #008080;">then</span>
             <span style="color: #000000;">a</span> <span style="color: #0000FF;">&=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">)</span>
             <span style="color: #000000;">adt</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">bdt</span>
         <span style="color: #008080;">elsif</span> <span style="color: #000000;">adt</span><span style="color: #0000FF;">></span><span style="color: #000000;">bdt</span> <span style="color: #008080;">then</span>
             <span style="color: #000000;">b</span> <span style="color: #0000FF;">&=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">-</span><span style="color: #000000;">bdt</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #004080;">bool</span> <span style="color: #000000;">bNegate</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">false</span>
     <span style="color: #008080;">if</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)<</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">or</span> <span style="color: #0000FF;">(</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)=</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">and</span> <span style="color: #000000;">a_smaller</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">))</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">bNegate</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">true</span>
         <span style="color: #0000FF;">{</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">a</span><span style="color: #0000FF;">}</span>   <span style="color: #000080;font-style:italic;">-- ensure b is the shorter/smaller</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=-</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #0000FF;">-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">by</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
         <span style="color: #000000;">da</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;"><-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)?</span><span style="color: #000000;">0</span><span style="color: #0000FF;">:</span><span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">)</span>
         <span style="color: #000000;">db</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;"><-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)?</span><span style="color: #000000;">0</span><span style="color: #0000FF;">:</span><span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span><span style="color: #0000FF;">)</span>
         <span style="color: #000000;">digit</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">da</span> <span style="color: #0000FF;">-</span> <span style="color: #0000FF;">(</span><span style="color: #000000;">db</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">carry</span><span style="color: #0000FF;">)</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">zdx</span>
         <span style="color: #000000;">carry</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">digit</span><span style="color: #0000FF;"><=</span><span style="color: #000000;">0</span>
         <span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">[</span><span style="color: #000000;">digit</span><span style="color: #0000FF;">+</span><span style="color: #000000;">carry</span><span style="color: #0000FF;">*</span><span style="color: #000000;">base</span><span style="color: #0000FF;">]</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">i</span><span style="color: #0000FF;"><-</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">and</span> <span style="color: #000000;">carry</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">carry</span> <span style="color: #008080;">then</span> 
         <span style="color: #0000FF;">?</span><span style="color: #000000;">9</span><span style="color: #0000FF;">/</span><span style="color: #000000;">0</span>    <span style="color: #000080;font-style:italic;">-- should have set bNegate above...</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">adt</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">a</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..-</span><span style="color: #000000;">adt</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"."</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_trim</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">bNegate</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">return</span> <span style="color: #000000;">a</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #008080;">function</span> <span style="color: #000000;">b_mul</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
     <span style="color: #004080;">integer</span> <span style="color: #000000;">base</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">zdx</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'0'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">dpa</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">a</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">dpb</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'.'</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">),</span>
             <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">dpa</span> <span style="color: #008080;">then</span> <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">+=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">dpa</span><span style="color: #0000FF;">;</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">dpa</span><span style="color: #0000FF;">..</span><span style="color: #000000;">dpa</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">dpb</span> <span style="color: #008080;">then</span> <span style="color: #000000;">ndp</span> <span style="color: #0000FF;">+=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">dpb</span><span style="color: #0000FF;">;</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">dpb</span><span style="color: #0000FF;">..</span><span style="color: #000000;">dpb</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">""</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #004080;">string</span> <span style="color: #000000;">pos</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"0"</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">zdx</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
         <span style="color: #000080;font-style:italic;">-- balanced number systems</span>
         <span style="color: #004080;">string</span> <span style="color: #000000;">neg</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">pos</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">to</span> <span style="color: #000000;">1</span> <span style="color: #008080;">by</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
             <span style="color: #004080;">integer</span> <span style="color: #000000;">m</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span>
             <span style="color: #008080;">while</span> <span style="color: #000000;">m</span> <span style="color: #008080;">do</span>
                 <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;"><</span><span style="color: #000000;">0</span><span style="color: #0000FF;">?</span><span style="color: #000000;">neg</span><span style="color: #0000FF;">:</span><span style="color: #000000;">pos</span><span style="color: #0000FF;">),</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
                 <span style="color: #000000;">m</span> <span style="color: #0000FF;">+=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">m</span><span style="color: #0000FF;"><</span><span style="color: #000000;">0</span><span style="color: #0000FF;">?+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
             <span style="color: #000000;">pos</span> <span style="color: #0000FF;">&=</span> <span style="color: #008000;">'0'</span>
             <span style="color: #000000;">neg</span> <span style="color: #0000FF;">&=</span> <span style="color: #008000;">'0'</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">for</span> 
     <span style="color: #008080;">else</span>
         <span style="color: #000080;font-style:italic;">-- non-balanced (normal) number systems</span>
         <span style="color: #004080;">bool</span> <span style="color: #000000;">negative</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">false</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span> <span style="color: #008080;">then</span> <span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$];</span> <span style="color: #000000;">negative</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">true</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]=</span><span style="color: #008000;">'-'</span> <span style="color: #008080;">then</span> <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$];</span> <span style="color: #000000;">negative</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">not</span> <span style="color: #000000;">negative</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
         <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">to</span> <span style="color: #000000;">1</span> <span style="color: #008080;">by</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
             <span style="color: #004080;">integer</span> <span style="color: #000000;">m</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">zdx</span>
             <span style="color: #008080;">while</span> <span style="color: #000000;">m</span><span style="color: #0000FF;">></span><span style="color: #000000;">0</span> <span style="color: #008080;">do</span>
                 <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #000000;">pos</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
                 <span style="color: #000000;">m</span> <span style="color: #0000FF;">-=</span> <span style="color: #000000;">1</span>
             <span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
             <span style="color: #000000;">pos</span> <span style="color: #0000FF;">&=</span> <span style="color: #008000;">'0'</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">negative</span> <span style="color: #008080;">then</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">negate</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">if</span> <span style="color: #000000;">ndp</span> <span style="color: #008080;">then</span>
         <span style="color: #000000;">res</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">ndp</span><span style="color: #0000FF;">..-</span><span style="color: #000000;">ndp</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"."</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_trim</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">)</span>
     <span style="color: #008080;">return</span> <span style="color: #000000;">res</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
  
 <span style="color: #000080;font-style:italic;">-- [note 1] not surprisingly, the decimal output is somewhat cleaner/shorter when
 --          the decimal string inputs for a and c are used, whereas tests 1/2/5/7
 --          (the 3-based ones) look much better with all ternary string inputs.</span>
  
 <span style="color: #008080;">procedure</span> <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">name</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
 <span style="color: #000080;font-style:italic;">--string a = b2b("523.2391403749428",decimal,alphabet),         -- [see note 1]</span>
 <span style="color: #004080;">string</span> <span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b2b</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"+-0++0+.+-0++0+"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">balancedternary</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
        <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b2b</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"-436.436"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">decimal</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
 <span style="color: #000080;font-style:italic;">--     b = b2b("-++-0--.--0+-00+++-",balancedternary,alphabet),
 --     c = b2b("65.26748971193416",decimal,alphabet),           -- [see note 1]</span>
        <span style="color: #000000;">c</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b2b</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"+-++-.+-++-"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">balancedternary</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
        <span style="color: #000000;">d</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">c</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span>
        <span style="color: #000000;">r</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_mul</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">d</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">)</span>
     <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%s\n%s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">name</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #008000;">'='</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">name</span><span style="color: #0000FF;">))})</span>
     <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"      a = %.16g  %s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">b2dec</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">a</span><span style="color: #0000FF;">})</span>
     <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"      b = %.16g  %s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">b2dec</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">b</span><span style="color: #0000FF;">})</span>
     <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"      c = %.16g  %s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">b2dec</span><span style="color: #0000FF;">(</span><span style="color: #000000;">c</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">c</span><span style="color: #0000FF;">})</span>
 <span style="color: #000080;font-style:italic;">--  printf(1,"      d = %.16g  %s\n",{b2dec(d,alphabet),d})</span>
     <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"a*(b-c) = %.16g  %s\n\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">b2dec</span><span style="color: #0000FF;">(</span><span style="color: #000000;">r</span><span style="color: #0000FF;">,</span><span style="color: #000000;">alphabet</span><span style="color: #0000FF;">),</span><span style="color: #000000;">r</span><span style="color: #0000FF;">})</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
 <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"balanced ternary"</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">balancedternary</span><span style="color: #0000FF;">)</span>
 <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"balanced base 27"</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">balanced_base27</span><span style="color: #0000FF;">)</span>
 <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"decimal"</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">decimal</span><span style="color: #0000FF;">)</span>
 <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"binary"</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">binary</span><span style="color: #0000FF;">)</span>
 <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"ternary"</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">ternary</span><span style="color: #0000FF;">)</span>
 <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"hexadecimal"</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">hexadecimal</span><span style="color: #0000FF;">)</span>
 <span style="color: #000000;">test</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"septemvigesimal"</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">septemvigesimal</span><span style="color: #0000FF;">)</span>
<!--</syntaxhighlight>-->
The printed decimal output is inherently limited to IEEE 754 precision, hence I deliberately limited output (%.16g) 
because it is silly to try and go any higher, whereas the output from b_mul() is actually perfectly accurate, 
see [note 1] regarding decimal/ternary input, just above.
{{out}}
<pre>
balanced ternary
================
      a = 523.2391403749428  +-0++0+.+-0++0+
      b = -436.4359999999999  -++-0--.--0+-00+++-0-+---0-+0++++0--0000+00-+-+--+0-0-00--++0-+00---+0+-+++0+-0----0++
      c = 65.26748971193416  +-++-.+-++-
a*(b-c) = -262510.9026799813  ----000-0+0+.0+0-0-00---00--0-0+--+--00-0++-000++0-000-+0+-----+++-+-0+-+0+0++0+0-++-++0+---00++++

balanced base 27
================
      a = 523.2391403749428  AUJ.FLI
      b = -436.436  NKQ.YFDFTYSMHVANGXPVXHIZJRJWZD0PBGFJAEBAKOZODLY0ITEHPQLSQSGLFZUINATKCIKUVMWEWJMQ0COTS
      c = 65.26748971193416  BK.GF
a*(b-c) = -262510.9026799813  ZVPJ.CWNYQPEENDVDPNJZXKFGCLHKLCX0YIBOMETHFWWBTVUFAH0SEZMTBJDCRRAQIQCAWMKXSTPYUXYPK0LODUO

decimal
=======
      a = 523.239140374943  523.239140374942844078646547782350251486053955189757658893461362597165066300868770004
      b = -436.436  -436.436
      c = 65.26748971193415  65.267489711934156378600823045267489711934156378600823045267489711934156378600823045
a*(b-c) = -262510.9026799814  -262510.90267998140903693918986303277315826215892262734715612833785876513103053772667101895163734826631742752252837097627017862754285047634638652268078676654605120794218

binary
======
      a = 523.2391403749427  1000001011.001111010011100001001101101110011000100001011110100101001010100100000111001000111
      b = -436.436  -110110100.011011111001110110110010001011010000111001010110000001000001100010010011011101001
      c = 65.26748971193416  1000001.01000100011110100011010010101100110001100000111010111111101111001001001101111101
a*(b-c) = -262510.9026799814  -1000000000101101110.111001110001011000001001000001101110011111011100000100000100001000101011100011110010110001010100110111001011101001010000001110110100111110001101000000001111110101

ternary
=======
      a = 523.2391403749428  201101.0201101
      b = -436.4360000000001  -121011.102202211210021110012111201022222000202102010100101200200110122011122101110212
      c = 65.26748971193416  2102.02102
a*(b-c) = -262510.9026799813  -111100002121.2201010011100110022102110002120222120100001221111011202022012121122001201122110221112

hexadecimal
===========
      a = 523.2391403749427  20B.3D384DB9885E94A90723EF9CBCB174B443E45FFC41152FE0293416F15E3AC303A0F3799ED81589C62
      b = -436.436  -1B4.6F9DB22D0E5604189374BC6A7EF9DB22D0E5604189374BC6A7EF9DB22D0E5604189374BC6A7EF9DB2
      c = 65.26748971193416  41.447A34ACC60EBFBC937D5DC2E5A99CF8A021B641511E8D2B3183AFEF24DF5770B96A673E28086D905
a*(b-c) = -262510.9026799814  -4016E.E7160906E7DC10422DA508321819F4A637E5AEE668ED5163B12FCB17A732442F589975B7F24112B2E8F6E95EAD45803915EE26D20DF323D67CAEEC75D7BED68AA34E02F2B492257D66F028545FB398F60E

septemvigesimal
===============
      a = 523.2391403749428  JA.6C9
      b = -436.436  -G4.BKML7C5DJ8Q0KB39AIICH4HACN02OJKGPLOPG2D1MFBQI6LJ33F645JELD7I0Q6FNHG88E9M9GE3QO276
      c = 65.26748971193416  2B.76
a*(b-c) = -262510.9026799813  -D92G.OA1C42LM0N8N30HDAFKJNEIFEOB0BHP1DM6ILA9P797KPJ05MCE6OGMO54Q3I3NQ9DGB673C8BC2FQF1N82
</pre>

=== multiplication table ===
Without e notation, with hexadecimal across, septemvigesimal down, and balanced ternary contents!
<!--<syntaxhighlight lang="phix">(phixonline)-->
 <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"* |"</span><span style="color: #0000FF;">)</span>
 <span style="color: #008080;">for</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">12</span> <span style="color: #008080;">do</span>
     <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">" #%s %3s |"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">atm2b</span><span style="color: #0000FF;">(</span><span style="color: #000000;">j</span><span style="color: #0000FF;">,</span><span style="color: #000000;">hexadecimal</span><span style="color: #0000FF;">),</span><span style="color: #000000;">atm2b</span><span style="color: #0000FF;">(</span><span style="color: #000000;">j</span><span style="color: #0000FF;">,</span><span style="color: #000000;">balancedternary</span><span style="color: #0000FF;">)})</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
 <span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">27</span> <span style="color: #008080;">do</span>
     <span style="color: #004080;">string</span> <span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">atm2b</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #000000;">balancedternary</span><span style="color: #0000FF;">)</span>
     <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"\n%-2s|"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">atm2b</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #000000;">septemvigesimal</span><span style="color: #0000FF;">)})</span>
     <span style="color: #008080;">for</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">12</span> <span style="color: #008080;">do</span>
         <span style="color: #008080;">if</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">></span><span style="color: #000000;">i</span> <span style="color: #008080;">then</span>
             <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"        |"</span><span style="color: #0000FF;">)</span>
         <span style="color: #008080;">else</span>
             <span style="color: #004080;">string</span> <span style="color: #000000;">b</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">atm2b</span><span style="color: #0000FF;">(</span><span style="color: #000000;">j</span><span style="color: #0000FF;">,</span><span style="color: #000000;">balancedternary</span><span style="color: #0000FF;">)</span>
             <span style="color: #004080;">string</span> <span style="color: #000000;">m</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">b_mul</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">balancedternary</span><span style="color: #0000FF;">)</span>
             <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">" %6s |"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">m</span><span style="color: #0000FF;">})</span>
         <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
     <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
 <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
 <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"\n"</span><span style="color: #0000FF;">)</span>
<!--</syntaxhighlight>-->
{{out}}
<pre>
* | #1   + | #2  +- | #3  +0 | #4  ++ | #5 +-- | #6 +-0 | #7 +-+ | #8 +0- | #9 +00 | #A +0+ | #B ++- | #C ++0 |
1 |      + |        |        |        |        |        |        |        |        |        |        |        |
2 |     +- |     ++ |        |        |        |        |        |        |        |        |        |        |
3 |     +0 |    +-0 |    +00 |        |        |        |        |        |        |        |        |        |
4 |     ++ |    +0- |    ++0 |   +--+ |        |        |        |        |        |        |        |        |
5 |    +-- |    +0+ |   +--0 |   +-+- |   +0-+ |        |        |        |        |        |        |        |
6 |    +-0 |    ++0 |   +-00 |   +0-0 |   +0+0 |   ++00 |        |        |        |        |        |        |
7 |    +-+ |   +--- |   +-+0 |   +00+ |   ++0- |  +---0 |  +--++ |        |        |        |        |        |
8 |    +0- |   +--+ |   +0-0 |   ++-- |   ++++ |  +--+0 |  +-0+- |  +-+0+ |        |        |        |        |
9 |    +00 |   +-00 |   +000 |   ++00 |  +--00 |  +-000 |  +-+00 |  +0-00 |  +0000 |        |        |        |
A |    +0+ |   +-+- |   +0+0 |   ++++ |  +-0-- |  +-+-0 |  +0--+ |  +000- |  +0+00 |  ++-0+ |        |        |
B |    ++- |   +-++ |   ++-0 |  +--0- |  +-00+ |  +-++0 |  +00-- |  +0+-+ |  ++-00 |  ++0+- |  +++++ |        |
C |    ++0 |   +0-0 |   ++00 |  +--+0 |  +-+-0 |  +0-00 |  +00+0 |  ++--0 |  ++000 |  ++++0 | +--0-0 | +--+00 |
D |    +++ |   +00- |   +++0 |  +-0-+ |  +-++- |  +00-0 |  +0+0+ |  ++0-- |  +++00 | +---++ | +--+0- | +-0-+0 |
E |   +--- |   +00+ |  +---0 |  +-0+- |  +0--+ |  +00+0 |  ++-0- |  ++0++ | +---00 | +--+-- | +-0-0+ | +-0+-0 |
F |   +--0 |   +0+0 |  +--00 |  +-+-0 |  +0-+0 |  +0+00 |  ++0-0 |  ++++0 | +--000 | +-0--0 | +-00+0 | +-+-00 |
G |   +--+ |   ++-- |  +--+0 |  +-+0+ |  +000- |  ++--0 |  ++0++ | +---+- | +--+00 | +-00-+ | +-+--- | +-+0+0 |
H |   +-0- |   ++-+ |  +-0-0 |  +0--- |  +00++ |  ++-+0 |  ++++- | +--00+ | +-0-00 | +-0+0- | +-+0-+ | +0---0 |
I |   +-00 |   ++00 |  +-000 |  +0-00 |  +0+00 |  ++000 | +---00 | +--+00 | +-0000 | +-+-00 | +-++00 | +0-000 |
J |   +-0+ |   +++- |  +-0+0 |  +0-++ |  ++--- |  +++-0 | +--0-+ | +-0-0- | +-0+00 | +-+00+ | +0--+- | +0-++0 |
K |   +-+- |   ++++ |  +-+-0 |  +000- |  ++-0+ |  ++++0 | +--+-- | +-00-+ | +-+-00 | +-+++- | +0-0++ | +000-0 |
L |   +-+0 |  +---0 |  +-+00 |  +00+0 |  ++0-0 | +---00 | +--++0 | +-0+-0 | +-+000 | +0--+0 | +00--0 | +00+00 |
M |   +-++ |  +--0- |  +-++0 |  +0+-+ |  ++0+- | +--0-0 | +-0-0+ | +-+--- | +-++00 | +0-0++ | +0000- | +0+-+0 |
N |   +0-- |  +--0+ |  +0--0 |  +0++- |  +++-+ | +--0+0 | +-000- | +-+-++ | +0--00 | +00--- | +00+0+ | +0++-0 |
O |   +0-0 |  +--+0 |  +0-00 |  ++--0 |  ++++0 | +--+00 | +-0+-0 | +-+0+0 | +0-000 | +000-0 | +0+-+0 | ++--00 |
P |   +0-+ |  +-0-- |  +0-+0 |  ++-0+ | +---0- | +-0--0 | +-0+++ | +-+++- | +0-+00 | +00+-+ | +0++-- | ++-0+0 |
Q |   +00- |  +-0-+ |  +00-0 |  ++0-- | +---++ | +-0-+0 | +-+-+- | +0--0+ | +00-00 | +0+-0- | ++---+ | ++0--0 |
10|   +000 |  +-000 |  +0000 |  ++000 | +--000 | +-0000 | +-+000 | +0-000 | +00000 | +0+000 | ++-000 | ++0000 |
</pre>

=={{header|Wren}}==
{{trans|Phix}}
{{libheader|Wren-str}}
{{libheader|Wren-iterate}}
{{libheader|Wren-fmt}}
Translated via the Go entry.
<syntaxhighlight lang="wren">import "./str" for Str
import "./iterate" for Stepped
import "./fmt" for Fmt

var maxdp           = 81
var binary          = "01"
var ternary         = "012"
var balancedTernary = "-0+"
var decimal         = "0123456789"
var hexadecimal     = "0123456789ABCDEF"
var septemVigesimal = "0123456789ABCDEFGHIJKLMNOPQ"
var balancedBase27  = "ZYXWVUTSRQPON0ABCDEFGHIJKLM"
var base37          = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"

// converts Phix indices to Wren
var wIndex = Fn.new { |pIndex, le|
    if (pIndex < 0) return pIndex + le
    return pIndex - 1
}

var getCarry = Fn.new { |digit, base|
    if (digit > base) {
        return 1
    } else if (digit < 1) {
        return -1
    }
    return 0
}

// convert string 'b' to a decimal floating point number
var b2dec = Fn.new { |b, alphabet|
    var res = 0
    var base = alphabet.count
    var zdx = alphabet.indexOf("0") + 1
    var signed = zdx == 1 && b[0] == "-"
    if (signed) b = b[1..-1]
    var le = b.count
    var ndp = b.indexOf(".") + 1
    if (ndp != 0) {
        b = Str.delete(b, ndp - 1) // remove decimal point
        ndp = le - ndp
    }
    for (i in Stepped.ascend(1..b.count)) {
        var idx = alphabet.indexOf(b[i-1]) + 1
        res = base * res + idx - zdx
    }
    if (ndp != 0) res = res / base.pow(ndp)
    if (signed) res = -res
    return res
}

// string 'b' can be balanced or unbalanced
var negate = Fn.new { |b, alphabet|
    if (alphabet[0] == "0") {
        if (b != "0") b = (b[0] == "-") ? b[1..-1] : Str.insert(b, 0, "-")
    } else {
        for (i in Stepped.ascend(1..b.count)) {
            if (b[i-1] != ".") {
                var idx = alphabet.indexOf(b[i-1]) + 1
                var wi = wIndex.call(-idx, alphabet.count)
                b = Str.change(b, i-1, alphabet[wi])
            }
        }
    }
    return b
}

var bTrim = Fn.new { |b|
    // trim  trailing ".000"
    var idx = b.indexOf(".") + 1
    if (idx != 0) b = b.trimEnd("0").trimEnd(".")
    // trim leading zeros but not "0.nnn"
    while (b.count > 1 && b[0] == "0" && b[1] != ".") b = b[1..-1]
    return b
}

// for balanced number systems only
var bCarry = Fn.new { |digit, base, idx, n, alphabet|
    var carry = getCarry.call(digit, base)
    if (carry != 0) {
        for (i in Stepped.descend(idx..1)) {
            if (n[i-1] != ".") {
                var k = alphabet.indexOf(n[i-1]) + 1
                if (k < base) {
                    n = Str.change(n, i-1, alphabet[k])
                    break
                }
                n = Str.change(n, i-1, alphabet[0])
            }
        }
        digit = digit - base * carry
    }
    return [digit, n]
}

// convert a string from alphabet to alphabet2
var b2b // recursive function
b2b = Fn.new { |n, alphabet, alphabet2|
    var res = "0"
    var m = ""
    if (n != "0") {
        var base = alphabet.count
        var base2 = alphabet2.count
        var zdx = alphabet.indexOf("0") + 1
        var zdx2 = alphabet2.indexOf("0") + 1
        var carry = 0
        var q = 0
        var r = 0
        var digit = 0
        var idx = alphabet.indexOf(n[0]) + 1
        var negative = (zdx == 1 && n[0] == "-") || (zdx != 1 && idx < zdx)
        if (negative) n = negate.call(n, alphabet)
        var ndp = n.indexOf(".") + 1
        if (ndp != 0) {
            var t = n
            n = n[0...ndp-1]
            m = t[ndp..-1]
        }
        res = ""
        while (n.count > 0) {
            q = 0
            for (i in Stepped.ascend(1..n.count)) {
                digit = alphabet.indexOf(n[i-1]) + 1 - zdx
                q = q*base + digit
                r = q.abs % base2
                digit = (q.abs/base2).floor + zdx
                if (q < 0) digit = digit - 1
                if (zdx != 1) {
                    var p = bCarry.call(digit, base, i-1, n, alphabet)
                    digit = p[0]
                    n = p[1]
                }
                n = Str.change(n, i-1, alphabet[digit-1])
                q = r
            }
            r = r + zdx2
            if (zdx2 != 1) {
                r = r + carry
                carry = getCarry.call(r, base2)
                r = r - base2 * carry
            }
            res = Str.insert(res, 0, alphabet2[r-1])
            n = n.trimStart("0")
        }
        if (carry != 0) res = Str.insert(res, 0, alphabet2[carry+zdx2-1])
        if (m.count > 0) {
            res = res + "."
            ndp = 0
            if (zdx != 1) {
                var lm = m.count
                var alphaNew = base37[0...alphabet.count]
                m = b2b.call(m, alphabet, alphaNew)
                m = ("0" * (lm-m.count)) + m
                alphabet = alphaNew
                zdx = 1
            }
            while (m.count > 0 && ndp < maxdp) {
                q = 0
                for (i in Stepped.descend(m.count..1)) {
                    digit = alphabet.indexOf(m[i-1]) + 1 - zdx
                    q = q + digit * base2
                    r = q.abs % base + zdx
                    q = (q / base).truncate
                    if (q < 0) q = q - 1
                    m = Str.change(m, i-1, alphabet[r-1])
                }
                digit = q + zdx2
                if (zdx2 != 1) {
                    var p = bCarry.call(digit, base2, res.count, res, alphabet2)
                    digit = p[0]
                    res = p[1]
                }
                res = res + alphabet2[digit-1]
                m = m.trimEnd("0")
                ndp = ndp + 1
            }
        }
        res = bTrim.call(res)
        if (negative) res = negate.call(res, alphabet2)
    }
    return res
}

// convert 'd' to a string in the specified base
var float2b = Fn.new { |d, alphabet|
    var base = alphabet.count
    var zdx = alphabet.indexOf("0") + 1
    var carry = 0
    var neg = d < 0
    if (neg) d = -d
    var res = ""
    var whole = d.floor
    d = d - whole
    while (true) {
        var ch = whole % base + zdx
        if (zdx != 1) {
            ch = ch + carry
            carry = getCarry.call(ch, base)
            ch = ch - base * carry
        }
        res = Str.insert(res, 0, alphabet[ch-1])
        whole = (whole / base).truncate
        if (whole == 0) break
    }
    if (carry != 0) {
        res = Str.insert(res, 0, alphabet[carry+zdx-1])
        carry = 0
    }
    if (d != 0) {
        res = res + "."
        var ndp = 0
        while (d != 0 && ndp < maxdp) {
            d = d * base
            var digit = d.truncate + zdx
            d = d - digit
            if (zdx != 1) {
                var p = bCarry.call(digit, base, res.count, res, alphabet)
                digit = p[0]
                res = p[1]
            }
            res = res + alphabet[digit-1]
            ndp = ndp + 1
        }
    }
    if (neg) res = negate.call(res, alphabet)
    return res
}

var bSub // forwward declaration

var bAdd = Fn.new { |a, b, alphabet|
    var base = alphabet.count
    var zdx = alphabet.indexOf("0") + 1
    var carry = 0
    var da = 0
    var db = 0
    var digit = 0
    if (zdx == 1) {
        if (a[0] == "-") {
            return bSub.call(b, negate.call(a, alphabet), alphabet)
        }
        if (b[0] == "-") {
            return bSub.call(a, negate.call(b, alphabet), alphabet)
        }
    }
    var adt = a.indexOf(".") + 1
    var bdt = b.indexOf(".") + 1
    if (adt != 0 || bdt != 0) {
        if (adt != 0) {
            adt = a.count - adt + 1
            var wi = wIndex.call(-adt, a.count)
            a = Str.delete(a, wi)
        }
        if (bdt != 0) {
            bdt = b.count - bdt + 1
            var wi = wIndex.call(-bdt, b.count)
            b = Str.delete(b, wi)
        }
        if (bdt > adt) {
            a = a + ("0" * (bdt-adt))
            adt = bdt
        } else if (adt > bdt) {
            b = b + ("0" * (adt-bdt))
        }
    }
    if (a.count < b.count) {
       var t = a
       a = b
       b = t
    }
    for (i in Stepped.descend(-1..-a.count)) {
        if (i < -a.count) {
            da = 0
        } else {
            da = alphabet.indexOf(a[a.count + i]) + 1 - zdx
        }
        if (i < -b.count) {
            db = 0
        } else {
            db = alphabet.indexOf(b[b.count + i]) + 1 - zdx
        }
        digit = da + db + carry + zdx
        carry = getCarry.call(digit, base)
        a = Str.change(a, i + a.count, alphabet[digit-carry*base-1])
        if (i < -b.count && carry == 0) break
    }
    if (carry != 0) {
        a = Str.insert(a, 0, alphabet[carry+zdx-1])
    }
    if (adt != 0) {
        var wi = wIndex.call(-adt+1, a.count)
        a = Str.insert(a, wi, ".")
    }
    a = bTrim.call(a)
    return a
}

var aSmaller = Fn.new { |a, b, alphabet|
    if (a.count != b.count) Fiber.abort("strings should be equal in length")
    for (i in Stepped.ascend(1..a.count)) {
        var da = alphabet.indexOf(a[i-1]) + 1
        var db = alphabet.indexof(b[i-1]) + 1
        if (da != db) return da < db
    }
    return false
}

// declared earlier
bSub = Fn.new { |a, b, alphabet|
    var base = alphabet.count
    var zdx = alphabet.indexOf("0") + 1
    var carry = 0
    var da = 0
    var db = 0
    var digit = 0
    if (zdx == 1) {
        if (a[0] == "-") {
            return negate.call(bAdd.call(negate.call(a, alphabet), b, alphabet), alphabet)
        }
        if (b[0] == "-") {
            return bAdd.call(a, negate.call(b, alphabet), alphabet)
        }
    }
    var adt = a.indexOf(".") + 1
    var bdt = b.indexOf(".") + 1
    if (adt != 0 || bdt != 0) {
        if (adt != 0) {
            adt = a.count - adt + 1
            var wi = wIndex.call(-adt, a.count)
            a = Str.delete(a, wi)
        }
        if (bdt != 0) {
            bdt = b.count - bdt + 1
            var wi = wIndex.call(-bdt, b.count)
            b = Str.delete(b, wi)
        }
        if (bdt > adt) {
            a = a + ("0" * (bdt-adt))
            adt = bdt
        } else if (adt > bdt) {
            b = b + ("0" * (adt-bdt))
        }
    }
    var bNegate = false
    if (a.count < b.count || (a.count == b.count && aSmaller.call(a, b, alphabet))) {
        bNegate = true
        var t = a
        a = b
        b = t
    }
    for (i in Stepped.descend(-1..-a.count)) {
        if (i < -a.count) {
            da = 0
        } else {
            da = alphabet.indexOf(a[a.count+i]) + 1 - zdx
        }
        if (i < -b.count) {
            db = 0
        } else {
            db = alphabet.indexOf(b[b.count+i]) + 1 - zdx
        }
        digit = da - db - carry + zdx
        carry = 0
        if (digit <= 0) carry = 1
        a = Str.change(a, i+a.count, alphabet[digit+carry*base-1])
        if (i < -b.count && carry == 0) break
    }
    if (carry != 0) Fiber.abort("carry should be zero")
    if (adt != 0) {
        var wi = wIndex.call(-adt+1, a.count)
        a = Str.insert(a, wi, ".")
    }
    a = bTrim.call(a)
    if (bNegate) a = negate.call(a, alphabet)
    return a
}

var bMul = Fn.new { |a, b, alphabet|
    var zdx = alphabet.indexOf("0") + 1
    var dpa = a.indexOf(".") + 1
    var dpb = b.indexOf(".") + 1
    var ndp = 0
    if (dpa != 0) {
        ndp = ndp + a.count - dpa
        a = Str.delete(a, dpa-1)
    }
    if (dpb != 0) {
        ndp = ndp + b.count - dpb
        b = Str.delete(b, dpb-1)
    }
    var pos = a
    var res = "0"
    if (zdx != 1) {
        // balanced number systems
        var neg = negate.call(pos, alphabet)
        for (i in Stepped.descend(b.count..1)) {
            var m = alphabet.indexOf(b[i-1]) + 1 - zdx
            while (m != 0) {
                var temp = pos
                var temp2 = -1
                if (m < 0) {
                    temp = neg
                    temp2 = 1
                }
                res = bAdd.call(res, temp, alphabet)
                m = m + temp2
            }
            pos = pos + "0"
            neg = neg + "0"
        }
    } else {
        // non-balanced number systems
        var negative = false
        if (a[0] == "-") {
            a = a[1..-1]
            negative = true
        }
        if (b[0] == "-") {
            b = b[1..-1]
            negative = !negative
        }
        for (i in Stepped.descend(b.count..1)) {
            var m = alphabet.indexOf(b[i-1]) + 1 - zdx
            while (m > 0) {
                res = bAdd.call(res, pos, alphabet)
                m = m - 1
            }
            pos = pos + "0"
        }
        if (negative) res = negate.call(res, alphabet)
    }
    if (ndp != 0) {
        var wi = wIndex.call(-ndp, res.count)
        res = Str.insert(res, wi, ".")
    }
    res = bTrim.call(res)
    return res
}

var multTable = Fn.new {
    System.print("multiplication table")
    System.print("====================")
    System.write("* |")
    for (j in 1..12) {
        Fmt.write(" #$s $3s |", float2b.call(j, hexadecimal), float2b.call(j, balancedTernary))
    }
    for (i in 1..27) {
        var a = float2b.call(i, balancedTernary)
        Fmt.write("\n$-2s|", float2b.call(i, septemVigesimal))
        for (j in 1..12) {
            if (j > i) {
                System.write("        |")
            } else {
                var b = float2b.call(j, balancedTernary)
                var m = bMul.call(a, b, balancedTernary)
                Fmt.write(" $6s |", m)
            }
        }
    }
    System.print()
}

var test = Fn.new {|name, alphabet|
    var a = b2b.call("+-0++0+.+-0++0+", balancedTernary, alphabet)
    var b = b2b.call("-436.436", decimal, alphabet)
    var c = b2b.call("+-++-.+-++-", balancedTernary, alphabet)
    var d = bSub.call(b, c, alphabet)
    var r = bMul.call(a, d, alphabet)
    Fmt.print("$s\n$s", name, "=" * name.count)
    Fmt.print("      a = $.14f $s", b2dec.call(a, alphabet), a)
    Fmt.print("      b = $.14f $s", b2dec.call(b, alphabet), b)
    Fmt.print("      c = $.14f $s", b2dec.call(c, alphabet), c)
    Fmt.print("a*(b-c) = $.14f $s\n", b2dec.call(r, alphabet), r)
}

test.call("balanced ternary", balancedTernary)
test.call("balanced base 27", balancedBase27)
test.call("decimal", decimal)
test.call("binary", binary)
test.call("ternary", ternary)
test.call("hexadecimal", hexadecimal)
test.call("septemvigesimal", septemVigesimal)
multTable.call()</syntaxhighlight>

{{out}}
<pre>
balanced ternary
================
      a = 523.23914037494285 +-0++0+.+-0++0+
      b = -436.43599999999992 -++-0--.--0+-00+++-0-+---0-+0++++0--0000+00-+-+--+0-0-00--++0-+00---+0+-+++0+-0----0++
      c = 65.26748971193416 +-++-.+-++-
a*(b-c) = -262510.90267998125637 ----000-0+0+.0+0-0-00---00--0-0+--+--00-0++-000++0-000-+0+-----+++-+-0+-+0+0++0+0-++-++0+---00++++

balanced base 27
================
      a = 523.23914037494285 AUJ.FLI
      b = -436.43600000000004 NKQ.YFDFTYSMHVANGXPVXHIZJRJWZD0PBGFJAEBAKOZODLY0ITEHPQLSQSGLFZUINATKCIKUVMWEWJMQ0COTS
      c = 65.26748971193416 BK.GF
a*(b-c) = -262510.90267998125637 ZVPJ.CWNYQPEENDVDPNJZXKFGCLHKLCX0YIBOMETHFWWBTVUFAH0SEZMTBJDCRRAQIQCAWMKXSTPYUXYPK0LODUO

decimal
=======
      a = 523.23914037494296 523.239140374942844078646547782350251486053955189757658893461362597165066300868770004
      b = -436.43599999999998 -436.436
      c = 65.26748971193415 65.267489711934156378600823045267489711934156378600823045267489711934156378600823045
a*(b-c) = -262510.90267998137278 -262510.90267998140903693918986303277315826215892262734715612833785876513103053772667101895163734826631742752252837097627017862754285047634638652268078676654605120794218

binary
======
      a = 523.23914037494274 1000001011.001111010011100001001101101110011000100001011110100101001010100100000111001000111
      b = -436.43600000000004 -110110100.011011111001110110110010001011010000111001010110000001000001100010010011011101001
      c = 65.26748971193416 1000001.01000100011110100011010010101100110001100000111010111111101111001001001101111101
a*(b-c) = -262510.90267998143099 -1000000000101101110.111001110001011000001001000001101110011111011100000100000100001000101011100011110010110001010100110111001011101001010000001110110100111110001101000000001111110101

ternary
=======
      a = 523.23914037494285 201101.0201101
      b = -436.43600000000021 -121011.102202211210021110012111201022222000202102010100101200200110122011122101110212
      c = 65.26748971193416 2102.02102
a*(b-c) = -262510.90267998125637 -111100002121.2201010011100110022102110002120222120100001221111011202022012121122001201122110221112

hexadecimal
===========
      a = 523.23914037494274 20B.3D384DB9885E94A90723EF9CBCB174B443E45FFC41152FE0293416F15E3AC303A0F3799ED81589C62
      b = -436.43599999999998 -1B4.6F9DB22D0E5604189374BC6A7EF9DB22D0E5604189374BC6A7EF9DB22D0E5604189374BC6A7EF9DB2
      c = 65.26748971193416 41.447A34ACC60EBFBC937D5DC2E5A99CF8A021B641511E8D2B3183AFEF24DF5770B96A673E28086D905
a*(b-c) = -262510.90267998143099 -4016E.E7160906E7DC10422DA508321819F4A637E5AEE668ED5163B12FCB17A732442F589975B7F24112B2E8F6E95EAD45803915EE26D20DF323D67CAEEC75D7BED68AA34E02F2B492257D66F028545FB398F60E

septemvigesimal
===============
      a = 523.23914037494285 JA.6C9
      b = -436.43600000000004 -G4.BKML7C5DJ8Q0KB39AIICH4HACN02OJKGPLOPG2D1MFBQI6LJ33F645JELD7I0Q6FNHG88E9M9GE3QO276
      c = 65.26748971193416 2B.76
a*(b-c) = -262510.90267998125637 -D92G.OA1C42LM0N8N30HDAFKJNEIFEOB0BHP1DM6ILA9P797KPJ05MCE6OGMO54Q3I3NQ9DGB673C8BC2FQF1N82

multiplication table
====================
* | #1   + | #2  +- | #3  +0 | #4  ++ | #5 +-- | #6 +-0 | #7 +-+ | #8 +0- | #9 +00 | #A +0+ | #B ++- | #C ++0 |
1 |      + |        |        |        |        |        |        |        |        |        |        |        |
2 |     +- |     ++ |        |        |        |        |        |        |        |        |        |        |
3 |     +0 |    +-0 |    +00 |        |        |        |        |        |        |        |        |        |
4 |     ++ |    +0- |    ++0 |   +--+ |        |        |        |        |        |        |        |        |
5 |    +-- |    +0+ |   +--0 |   +-+- |   +0-+ |        |        |        |        |        |        |        |
6 |    +-0 |    ++0 |   +-00 |   +0-0 |   +0+0 |   ++00 |        |        |        |        |        |        |
7 |    +-+ |   +--- |   +-+0 |   +00+ |   ++0- |  +---0 |  +--++ |        |        |        |        |        |
8 |    +0- |   +--+ |   +0-0 |   ++-- |   ++++ |  +--+0 |  +-0+- |  +-+0+ |        |        |        |        |
9 |    +00 |   +-00 |   +000 |   ++00 |  +--00 |  +-000 |  +-+00 |  +0-00 |  +0000 |        |        |        |
A |    +0+ |   +-+- |   +0+0 |   ++++ |  +-0-- |  +-+-0 |  +0--+ |  +000- |  +0+00 |  ++-0+ |        |        |
B |    ++- |   +-++ |   ++-0 |  +--0- |  +-00+ |  +-++0 |  +00-- |  +0+-+ |  ++-00 |  ++0+- |  +++++ |        |
C |    ++0 |   +0-0 |   ++00 |  +--+0 |  +-+-0 |  +0-00 |  +00+0 |  ++--0 |  ++000 |  ++++0 | +--0-0 | +--+00 |
D |    +++ |   +00- |   +++0 |  +-0-+ |  +-++- |  +00-0 |  +0+0+ |  ++0-- |  +++00 | +---++ | +--+0- | +-0-+0 |
E |   +--- |   +00+ |  +---0 |  +-0+- |  +0--+ |  +00+0 |  ++-0- |  ++0++ | +---00 | +--+-- | +-0-0+ | +-0+-0 |
F |   +--0 |   +0+0 |  +--00 |  +-+-0 |  +0-+0 |  +0+00 |  ++0-0 |  ++++0 | +--000 | +-0--0 | +-00+0 | +-+-00 |
G |   +--+ |   ++-- |  +--+0 |  +-+0+ |  +000- |  ++--0 |  ++0++ | +---+- | +--+00 | +-00-+ | +-+--- | +-+0+0 |
H |   +-0- |   ++-+ |  +-0-0 |  +0--- |  +00++ |  ++-+0 |  ++++- | +--00+ | +-0-00 | +-0+0- | +-+0-+ | +0---0 |
I |   +-00 |   ++00 |  +-000 |  +0-00 |  +0+00 |  ++000 | +---00 | +--+00 | +-0000 | +-+-00 | +-++00 | +0-000 |
J |   +-0+ |   +++- |  +-0+0 |  +0-++ |  ++--- |  +++-0 | +--0-+ | +-0-0- | +-0+00 | +-+00+ | +0--+- | +0-++0 |
K |   +-+- |   ++++ |  +-+-0 |  +000- |  ++-0+ |  ++++0 | +--+-- | +-00-+ | +-+-00 | +-+++- | +0-0++ | +000-0 |
L |   +-+0 |  +---0 |  +-+00 |  +00+0 |  ++0-0 | +---00 | +--++0 | +-0+-0 | +-+000 | +0--+0 | +00--0 | +00+00 |
M |   +-++ |  +--0- |  +-++0 |  +0+-+ |  ++0+- | +--0-0 | +-0-0+ | +-+--- | +-++00 | +0-0++ | +0000- | +0+-+0 |
N |   +0-- |  +--0+ |  +0--0 |  +0++- |  +++-+ | +--0+0 | +-000- | +-+-++ | +0--00 | +00--- | +00+0+ | +0++-0 |
O |   +0-0 |  +--+0 |  +0-00 |  ++--0 |  ++++0 | +--+00 | +-0+-0 | +-+0+0 | +0-000 | +000-0 | +0+-+0 | ++--00 |
P |   +0-+ |  +-0-- |  +0-+0 |  ++-0+ | +---0- | +-0--0 | +-0+++ | +-+++- | +0-+00 | +00+-+ | +0++-- | ++-0+0 |
Q |   +00- |  +-0-+ |  +00-0 |  ++0-- | +---++ | +-0-+0 | +-+-+- | +0--0+ | +00-00 | +0+-0- | ++---+ | ++0--0 |
10|   +000 |  +-000 |  +0000 |  ++000 | +--000 | +-0000 | +-+000 | +0-000 | +00000 | +0+000 | ++-000 | ++0000 |
</pre>

[[Category:Arbitrary precision]]