Horner's rule for polynomial evaluation: Difference between revisions
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Line 20:
Cf. [[Formal power series]]
=={{header|11l}}==
{{trans|Python}}
<syntaxhighlight lang="11l">F horner(coeffs, x)
V acc = 0
L(c) reversed(coeffs)
acc = acc * x + c
R acc
print(horner([-19, 7, -4, 6], 3))</syntaxhighlight>
{{out}}
<pre>
128
</pre>
=={{header|360 Assembly}}==
<
HORNER CSECT
USING HORNER,R15 set base register
Line 42 ⟶ 58:
PG DS CL12 buffer
YREGS
END HORNER</
{{out}}
<pre>
Line 49 ⟶ 65:
=={{header|ACL2}}==
<
(if (endp ps)
0
(+ (first ps)
(* x (horner (rest ps) x)))))</
=={{header|Action!}}==
<syntaxhighlight lang="action!">INT FUNC Horner(INT ARRAY coeffs INT count,x)
INT v,i
v=0 i=count-1
WHILE i>=0
DO
v=v*x+coeffs(i)
i==-1
OD
RETURN (v)
PROC Main()
INT ARRAY coeffs=[65517 7 65532 6]
INT res,x=[3],i,count=[4]
PrintF("x=%I%E",x)
FOR i=0 TO count-1
DO
PrintI(coeffs(i))
IF i=1 THEN
Print("x")
ELSEIF i>1 THEN
PrintF("x^%I",i)
FI
IF i<count-1 AND coeffs(i+1)>=0 THEN
Print("+")
FI
OD
res=Horner(coeffs,4,x)
PrintF("=%I%E",res)
RETURN</syntaxhighlight>
{{out}}
[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Horner's_rule_for_polynomial_evaluation.png Screenshot from Atari 8-bit computer]
<pre>
x=3
-19+7x-4x^2+6x^3=128
</pre>
=={{header|Ada}}==
<
procedure Horners_Rule is
Line 72 ⟶ 127:
begin
Put(Horner(Coeffs => (-19.0, 7.0, -4.0, 6.0), Val => 3.0), Aft=>1, Exp=>0);
end Horners_Rule;</
Output:
<pre>128.0</pre>
=={{header|Aime}}==
<
horner(list coeffs, real x)
{
z = 0;
}
}
integer
main(void)
{
}</
=={{header|ALGOL 68}}==
{{works with|ALGOL 68G}}
<
(
REAL res := 0.0;
Line 118 ⟶ 170:
[4]REAL coeffs := (-19.0, 7.0, -4.0, 6.0);
print( horner(coeffs, 3.0) )
)</
=={{header|ALGOL W}}==
<syntaxhighlight lang="algolw">begin
% Horner's rule for polynominal evaluation %
% returns the value of the polynominal defined by coefficients, %
% at the point x. The number of coefficients must be in ub %
% the coefficients should be in order with x^0 first, x^n last %
real procedure Horner( real array coefficients ( * )
; integer value ub
; real value x
) ;
begin
real xValue;
xValue := 0;
for i := ub step -1 until 1 do xValue := ( xValue * x ) + coefficients( i );
xValue
end Horner ;
% task test case %
begin
real array coefficients ( 1 :: 4 );
integer cPos;
cPos := 1;
for i := -19, 7, -4, 6 do begin
coefficients( cPos ) := i;
cPos := cPos + 1
end for_i ;
write( r_format := "A", r_w := 8, r_d := 2, Horner( coefficients, 4, 3 ) )
end test_cases
end.</syntaxhighlight>
{{out}}
<pre>
128.00
</pre>
=={{header|APL}}==
Works in [[Dyalog APL]]
<syntaxhighlight lang="apl">h←⊥∘⌽</syntaxhighlight>
{{output}}
<pre>
3 h ¯19 7 ¯4 6
128
</pre>
=={{header|ATS}}==
<
"share/atspre_staload.hats"
Line 144 ⟶ 238:
in
println! (res)
end // end of [main0]</
=={{header|Arturo}}==
<syntaxhighlight lang="rebol">horner: function [coeffs, x][
result: 0
loop reverse coeffs 'c ->
result: c + result * x
return result
]
print horner @[neg 19, 7, neg 4, 6] 3</syntaxhighlight>
{{out}}
<pre>128</pre>
=={{header|AutoHotkey}}==
<
x := 3
Line 162 ⟶ 268:
i := Co0 - A_Index + 1, Result := Result * x + Co%i%
Return, Result
}</
Message box shows:
<pre>128</pre>
=={{header|AWK}}==
<
function horner(x, A) {
acc = 0;
Line 178 ⟶ 284:
split(p,P);
print horner(x,P);
}</
{{out}}
Line 185 ⟶ 291:
128
</pre>
=={{header|BASIC}}==
==={{header|Applesoft BASIC}}===
{{works with|Chipmunk Basic}}
{{works with|GW-BASIC}}
<syntaxhighlight lang="qbasic">100 HOME : REM 100 CLS for Chipmunk Basic and GW-BASIC
100 CLS : REM 100 HOME for Applesoft BASIC
110 X = 3
120 DIM COEFFS(3)
130 COEFFS(0) = -19
140 COEFFS(1) = 7
150 COEFFS(2) = -4
160 COEFFS(3) = 6
170 PRINT "Horner's algorithm for the polynomial "
180 PRINT "6*x^3 - 4*x^2 + 7*x - 19 when x = 3 is: ";
190 ACCUM = 0
200 FOR I = 3 TO 0 STEP -1
210 ACCUM = (ACCUM*X)+COEFFS(I)
220 NEXT I
230 PRINT ACCUM
240 END</syntaxhighlight>
==={{header|BASIC256}}===
<syntaxhighlight lang="vb">x = 3
dim coeficientes = {-19, 7, -4, 6}
print "Horner's algorithm for the polynomial ";
print "6*x^3 - 4*x^2 + 7*x - 19 when x = 3: ";
print AlgoritmoHorner(coeficientes, x)
end
function AlgoritmoHorner(coeffs, x)
acumulador = 0
for i = coeffs[?]-1 to 0 step -1
acumulador = (acumulador * x) + coeffs[i]
next i
return acumulador
end function</syntaxhighlight>
{{out}}
<pre>Same as FreeBASIC entry.</pre>
==={{header|Chipmunk Basic}}===
{{works with|Chipmunk Basic|3.6.4}}
{{works with|QBasic}}
<syntaxhighlight lang="qbasic">100 CLS
110 x = 3
120 DIM coeffs(3)
130 coeffs(0) = -19
140 coeffs(1) = 7
150 coeffs(2) = -4
160 coeffs(3) = 6
170 PRINT "Horner's algorithm for the polynomial "
180 PRINT "6*x^3 - 4*x^2 + 7*x - 19 when x = 3 is: ";
190 accum = 0
200 FOR i = UBOUND(coeffs,1) TO 0 STEP -1
210 accum = (accum*x)+coeffs(i)
220 NEXT i
230 PRINT accum
240 END</syntaxhighlight>
{{out}}
<pre>Horner's algorithm for the polynomial
6*x^3 - 4*x^2 + 7*x - 19 when x = 3 is: 128</pre>
==={{header|Gambas}}===
<syntaxhighlight lang="vbnet">Public coeficientes As New Integer[4]
Public Function AlgoritmoHorner(coeficientes As Integer[], x As Integer) As Integer
coeficientes[0] = -19
coeficientes[1] = 7
coeficientes[2] = -4
coeficientes[3] = 6
Dim i As Integer, acumulador As Integer = 0
For i = coeficientes.Count - 1 To 0 Step -1
acumulador = (acumulador * x) + coeficientes[i]
Next
Return acumulador
End Function
Public Sub Main()
Dim x As Integer = 3
Print "Horner's algorithm for the polynomial 6*x^3 - 4*x^2 + 7*x - 19 when x = 3: ";
Print AlgoritmoHorner(coeficientes, x)
End </syntaxhighlight>
{{out}}
<pre>Same as FreeBASIC entry.</pre>
==={{header|GW-BASIC}}===
{{works with|BASICA}}
{{works with|Chipmunk Basic}}
{{works with|PC-BASIC|any}}
{{works with|QBasic}}
<syntaxhighlight lang="qbasic">100 CLS : REM 100 HOME for Applesoft BASIC
110 X = 3
120 DIM COEFFS(3)
130 COEFFS(0) = -19
140 COEFFS(1) = 7
150 COEFFS(2) = -4
160 COEFFS(3) = 6
170 PRINT "Horner's algorithm for the polynomial "
180 PRINT "6*x^3 - 4*x^2 + 7*x - 19 when x = 3 is: ";
190 ACCUM = 0
200 FOR I = 3 TO 0 STEP -1
210 ACCUM = (ACCUM*X)+COEFFS(I)
220 NEXT I
230 PRINT ACCUM
240 END</syntaxhighlight>
{{out}}
<pre>Same as Chipmunk Basic entry.</pre>
==={{header|Minimal BASIC}}===
{{works with|QBasic}}
{{works with|QuickBasic}}
{{works with|Applesoft BASIC}}
{{works with|BASICA}}
{{works with|Chipmunk Basic}}
{{works with|GW-BASIC}}
{{works with|MSX BASIC}}
{{works with|Just BASIC}}
{{works with|Liberty BASIC}}
{{works with|Run BASIC}}
{{works with|Yabasic}}
<syntaxhighlight lang="qbasic">20 LET X = 3
30 DIM C(3)
40 LET C(0) = -19
50 LET C(1) = 7
60 LET C(2) = -4
70 LET C(3) = 6
80 PRINT "HORNER'S ALGORITHM FOR THE POLYNOMIAL"
90 PRINT "6*X^3 - 4*X^2 + 7*X - 19 WHEN X = 3 : ";
100 LET A = 0
110 FOR I = 3 TO 0 STEP -1
120 LET A = (A*X)+C(I)
130 NEXT I
140 PRINT A
150 END</syntaxhighlight>
{{out}}
<pre>Same as Chipmunk Basic entry.</pre>
==={{header|MSX Basic}}===
The [[#Minimal_BASIC|Minimal BASIC]] solution works without any changes.
==={{header|QBasic}}===
{{works with|QBasic|1.1}}
{{works with|QuickBasic|4.5}}
<syntaxhighlight lang="qbasic">FUNCTION Horner (coeffs(), x)
acumulador = 0
FOR i = UBOUND(coeffs) TO LBOUND(coeffs) STEP -1
acumulador = (acumulador * x) + coeffs(i)
NEXT i
Horner = acumulador
END FUNCTION
x = 3
DIM coeffs(3)
DATA -19, 7, -4, 6
FOR a = LBOUND(coeffs) TO UBOUND(coeffs)
READ coeffs(a)
NEXT a
PRINT "Horner's algorithm for the polynomial 6*x^3 - 4*x^2 + 7*x - 19 when x = 3 is: ";
PRINT Horner(coeffs(), x)
END</syntaxhighlight>
==={{header|Quite BASIC}}===
The [[#Minimal_BASIC|Minimal BASIC]] solution works without any changes.
==={{header|Yabasic}}===
<syntaxhighlight lang="vb">x = 3
dim coeffs(4)
coeffs(0) = -19
coeffs(1) = 7
coeffs(2) = -4
coeffs(3) = 6
print "Horner's algorithm for the polynomial ";
print "6*x^3 - 4*x^2 + 7*x - 19 when x = 3: ";
print AlgoritmoHorner(coeffs, x)
end
sub AlgoritmoHorner(coeffs, x)
local acumulador, i
acumulador = 0
for i = arraysize(coeffs(),1) to 0 step -1
acumulador = (acumulador * x) + coeffs(i)
next i
return acumulador
end sub</syntaxhighlight>
{{out}}
<pre>Same as FreeBASIC entry.</pre>
=={{header|Batch File}}==
<
@echo off
Line 211 ⟶ 511:
echo %return%
exit /b
</syntaxhighlight>
{{out}}
<pre>
Line 219 ⟶ 519:
128
</pre>
=={{header|BBC BASIC}}==
<
coefficients() = -19, 7, -4, 6
PRINT FNhorner(coefficients(), 3)
Line 232 ⟶ 531:
v = v * x + coeffs(i%)
NEXT
= v</
=={{header|Bracmat}}==
<
= accumulator coefficients x coeff
. !arg:(?coefficients.?x)
Line 246 ⟶ 545:
)
& Horner$(-19 7 -4 6.3)
);</
Output:
<pre>128</pre>
Line 252 ⟶ 551:
=={{header|C}}==
{{trans|Fortran}}
<
double horner(double *coeffs, int s, double x)
Line 273 ⟶ 572:
printf("%5.1f\n", horner(coeffs, sizeof(coeffs)/sizeof(double), 3.0));
return 0;
}</
=={{header|C sharp|C#}}==
<
using System.Linq;
Line 291 ⟶ 590:
Console.WriteLine(Horner(new[] { -19.0, 7.0, -4.0, 6.0 }, 3.0));
}
}</
Output:
<pre>128</pre>
Line 298 ⟶ 597:
The same C function works too, but another solution could be:
<
#include <vector>
Line 318 ⟶ 617:
cout << horner(v, 3.0) << endl;
return 0;
}</
Yet another solution, which is more idiomatic in C++ and works on any bidirectional sequence:
<
#include <iostream>
Line 339 ⟶ 638:
std::cout << horner(c, c + 4, 3) << std::endl;
}
</syntaxhighlight>
=={{header|Clojure}}==
<
(reduce #(-> %1 (* x) (+ %2)) (reverse coeffs)))
(println (horner [-19 7 -4 6] 3))</
=={{header|CoffeeScript}}==
<
eval_poly = (x, coefficients) ->
# coefficients are for ascending powers
Line 358 ⟶ 657:
console.log eval_poly 10, [4, 3, 2, 1] # 1234
console.log eval_poly 2, [1, 1, 0, 0, 1] # 19
</syntaxhighlight>
=={{header|Common Lisp}}==
<
(reduce #'(lambda (coef acc) (+ (* acc x) coef))
coeffs :from-end t :initial-value 0))</
Alternate version using LOOP. Coefficients are passed in a vector.
<
(loop :with y = 0
:for i :from (1- (length a)) :downto 0
Line 373 ⟶ 672:
:finally (return y)))
(horner 1.414 #(-2 0 1))</
=={{header|D}}==
The poly() function of the standard library std.math module uses Horner's rule:
<
void main() {
import std.stdio, std.math;
Line 385 ⟶ 684:
poly(x,pp).writeln;
}
}</
Basic implementation:
<
CommonType!(U, V) horner(U, V)(U[] p, V x) pure nothrow @nogc {
Line 398 ⟶ 697:
void main() {
[-19, 7, -4, 6].horner(3.0).writeln;
}</
More functional style:
<
auto horner(T, U)(in T[] p, in U x) pure nothrow @nogc {
Line 408 ⟶ 707:
void main() {
[-19, 7, -4, 6].horner(3.0).writeln;
}</
=={{header|Delphi}}==
{{works with|Delphi|6.0}}
{{libheader|Classes,SysUtils,StdCtrls}}
<syntaxhighlight lang="Delphi">
function EvaluatePolynomial(Args: array of double; X: double): double;
{Evaluate polynomial using Horner's rule }
var I: integer;
begin
Result:=0;
for I:=High(Args) downto 0 do
Result:=(Result * X ) + Args[I];
end;
function GetPolynomialStr(Args: array of double; VarName: string): string;
{Return a string display the polynomial in normal format}
{for example: 6.0 X^3 - 4.0 X^2 + 7.0 X - 19.0}
var I: integer;
begin
Result:='';
for I:=High(Args) downto 0 do
begin
if Args[I]>0 then
begin
if I<>High(Args) then Result:=Result+' + ';
end
else Result:=Result+' - ';
Result:=Result+FloatToStrF(Abs(Args[I]),ffFixed,18,1);
if I>0 then Result:=Result+' '+VarName;
if I>1 then Result:=Result+'^'+IntToStr(I);
end;
end;
procedure ShowHornerPoly(Memo: TMemo; Args: array of double; X: double);
{Evaluate polynomial, show formated polynomal and the result}
var R: double;
begin
R:=EvaluatePolynomial(Args,X);
Memo.Lines.Add(FloatToStrF(R,ffFixed, 18,1));
Memo.Lines.Add(GetPolynomialStr(Args,'X'));
end;
procedure DoHornerPoly(Memo: TMemo);
begin
ShowHornerPoly(Memo,[-19, 7, -4, 6],3)
end;
</syntaxhighlight>
{{out}}
<pre>
128.0
6.0 X^3 - 4.0 X^2 + 7.0 X - 19.0
</pre>
=={{header|E}}==
<
def indexing := (0..!coefficients.size()).descending()
return def hornerPolynomial(x) {
Line 421 ⟶ 779:
return acc
}
}</
<
# value: 128</
=={{header|EasyLang}}==
{{trans|C}}
<syntaxhighlight>
func horner coeffs[] x .
for i = len coeffs[] downto 1
res = res * x + coeffs[i]
.
return res
.
print horner [ -19 7 -4 6 ] 3
</syntaxhighlight>
{{out}}
<pre>
128
</pre>
=={{header|EchoLisp}}==
=== Functional version ===
<
(define (horner x poly)
(foldr (lambda (coeff acc) (+ coeff (* acc x))) 0 poly))
(horner 3 '(-19 7 -4 6)) → 128
</syntaxhighlight>
=== Library ===
<
(lib 'math)
Lib: math.lib loaded.
Line 442 ⟶ 816:
(poly->string 'x P) → 6x^3 -4x^2 +7x -19
(poly 3 P) → 128
</syntaxhighlight>
=={{header|EDSAC order code}}==
<syntaxhighlight lang="edsac">
[Copyright <2021> <ERIK SARGSYAN>
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.]
[Horner's rule for polynomial evaluation on EDSAC by Erik Sargsyan]
[EDSAC program, Initial Orders 2]
T 56 K
GK
[0] A 3 F
[1] T 9 F
[2] A 4 F [loading the address of the 1st array element into the accumulator]
[3] A 14 @ [add an instruction code with a zero address field]
[4] T 14 @ [writing the generated instruction, zeroing the accumulator]
[5 loop] A 1 F [load the counter of unprocessed array elements into the accumulator]
[6] S 21 @ [Subtract the constant = 1]
[7] E 10 @ [if (acc >= 0) goto 10 else end]
[8] T 300 F [zeroing the accumulator]
[9] E 0 F [breakpoint, end of program]
[10] T 1 F [update the counter value and reset the accumulator]
[11] V 2 F [multiplying the number in cell 2 by the number in the multiplier register]
[12] L 1024 F [shift the number in the accumulator 12 bits to the left]
[13] L 4 F [shift the number in the accumulator 4 bits to the left]
[14 r1] A 0 F [loading the value from cell 0 into the accumulator]
[15] T 2 F [writing this value to the working cell, zeroing the accumulator]
[16] A 21 @ [loading into accumulator constant value = 1]
[17] L 0 D [shift the number in the accumulator 1 bit to the left]
[18] A 14 @ [add the code of the instruction executed in the previous step]
[19] T 14 @ [write the generated instruction into memory]
[20] E 5 @ [repeat all operations; accumulator zeroed]
[21 const 1] P 0 D [1]
GK
[0] H 10 @ [writing X0 to the multiplier register]
[1] A 11 @ [loading into the accumulator of the degree of the polynomial]
[2] T 1 F [writing the degree of a polynomial in cell 1]
[3] A 13 @ [loading the leading coefficient into the accumulator]
[4] T 2 F [writing the senior coefficient to the working cell 2]
[5] A 12 @ [loading the address of the 1st array element into the accumulator]
[6] T 4 F [writing the address of the 1st element of the array]
[7] A 7 @ [\ call]
[8] G 56 F
[9] Z 0 F
[10] P 3 F [X0 is a fixed value of X, by which we calculate the value of the polynomial]
[11 power] P 2 F [polynomial degree times 2]
[12 addr] P 14 @ [address of the 1st element of the array]
[13] P 3 F [a4 = 6]
[14] P 8 D [a3 = 17]
[15] P 9 F [a2 = 18]
[16] P 12 D [a1 = 25]
[17] P 316 F [a0 = 632]
EZPF
</syntaxhighlight>
{{out}}
<pre>
Cell 2 will contain the number 12878
</pre>
=={{header|Elena}}==
{{trans|C#}}
ELENA 5.0 :
<syntaxhighlight lang="elena">import extensions;
import system'routines;
horner(coefficients,variable)
{
^ coefficients.clone().sequenceReverse().accumulate(new Real(),(accumulator,coefficient => accumulator * variable + coefficient))
}
public program()
{
console.printLine(horner(new real[]{-19.0r, 7.0r, -4.0r, 6.0r}, 3.0r))
}</syntaxhighlight>
{{out}}
<pre>
128.0
</pre>
=={{header|Elixir}}==
<
IO.puts horner.([-19,7,-4,6], 3)</
{{out}}
Line 456 ⟶ 919:
=={{header|Emacs Lisp}}==
{{trans|Common Lisp}}
<syntaxhighlight lang="lisp">(require 'cl-lib)
(defun horner (coeffs x)
(cl-reduce #'(lambda (coef acc) (+ (* acc x) coef)
coeffs :from-end t :initial-value 0)
(horner '(-19 7 -4 6) 3)</syntaxhighlight>
{{out}}
128
=={{header|Erlang}}==
<
horner(L,X) ->
lists:foldl(fun(C, Acc) -> X*Acc+C end,0, lists:reverse(L)).
t() ->
horner([-19,7,-4,6], 3).
</syntaxhighlight>
=={{header|ERRE}}==
<syntaxhighlight lang="erre">
PROGRAM HORNER
Line 499 ⟶ 962:
PRINT(RES)
END PROGRAM
</syntaxhighlight>
=={{header|Euler Math Toolbox}}==
<syntaxhighlight lang="euler math toolbox">
>function horner (x,v) ...
$ n=cols(v); res=v{n};
Line 522 ⟶ 985:
3 2
6 x - 4 x + 7 x - 19
</syntaxhighlight>
=={{header|F Sharp|F#}}==
<
let horner l x =
List.rev l |> List.fold ( fun acc c -> x*acc+c) 0
horner [-19;7;-4;6] 3
</syntaxhighlight>
=={{header|Factor}}==
<
[ <reversed> 0 ] dip '[ [ _ * ] dip + ] reduce ;</
( scratchpad ) { -19 7 -4 6 } 3 horner .
Line 540 ⟶ 1,004:
=={{header|Forth}}==
<
0e
floats bounds ?do
Line 549 ⟶ 1,013:
create coeffs 6e f, -4e f, 7e f, -19e f,
coeffs 4 3e fhorner f. \ 128.</
=={{header|Fortran}}==
{{works with|Fortran|90 and later}}
<
implicit none
write (*, '(f5.1)') horner (
contains
Line 564 ⟶ 1,028:
implicit none
real, dimension (0:), intent (in) :: coeffs
real, intent (in) :: x
real :: res
integer :: i
res =
do i =
res = res * x + coeffs (i)
end do
Line 576 ⟶ 1,040:
end function horner
end program test_horner</
Output:
<pre>128.0</pre>
=== Fortran 77 ===
<
IMPLICIT NONE
INTEGER I,N
Line 590 ⟶ 1,054:
END DO
HORNER=Y
END</
As a matter of fact, computing the derivative is not much more difficult (see [http://www.cs.berkeley.edu/~wkahan/Math128/Poly.pdf Roundoff in Polynomial Evaluation], W. Kahan, 1986). The following subroutine computes both polynomial value and derivative for argument x.
<
C COMPUTE POLYNOMIAL VALUE AND DERIVATIVE
C SEE "ROUNDOFF IN POLYNOMIAL EVALUATION", W. KAHAN, 1986
Line 607 ⟶ 1,071:
Z = Z*X + Y
10 Y = Y*X + A(I)
END
</syntaxhighlight>
=={{header|FreeBASIC}}==
<syntaxhighlight lang="freebasic">
Function AlgoritmoHorner(coeffs() As Integer, x As Integer) As Integer
Dim As Integer i, acumulador = 0
For i = Ubound(coeffs, 1) To 0 Step -1
acumulador = (acumulador * x) + coeffs(i)
Next i
Return acumulador
End Function
Dim As Integer x = 3
Dim As Integer coeficientes(3) = {-19, 7, -4, 6}
Print "Algoritmo de Horner para el polinomio 6*x^3 - 4*x^2 + 7*x - 19 para x = 3: ";
Print AlgoritmoHorner(coeficientes(), x)
End
</syntaxhighlight>
{{out}}
<pre>
Algoritmo de Horner para el polinomio 6*x^3 - 4*x^2 + 7*x - 19 para x = 3: 128
</pre>
=={{header|FunL}}==
{{trans|Haskell}}
<
def horner( poly, x ) = foldr( \a, b -> a + b*x, 0, poly )
println( horner([-19, 7, -4, 6], 3) )</
{{out}}
Line 621 ⟶ 1,107:
<pre>
128
</pre>
=={{header|FutureBasic}}==
<syntaxhighlight lang="futurebasic">include "NSLog.incl"
local fn horner( coeffs as CFArrayRef, x as NSInteger ) as double
CFArrayRef reversedCoeffs
CFNumberRef num
double accumulator = 0.0
// Reverse coeffs array
reversedCoeffs = fn EnumeratorAllObjects( fn ArrayReverseObjectEnumerator( coeffs ) )
// Iterate over CFNumberRefs in reversed array, convert to double values, calculate and add to accumulator
for num in reversedCoeffs
accumulator = ( accumulator * x ) + fn NumberDoubleValue( num )
next
end fn = accumulator
CFArrayRef coeffs
coeffs = @[@-19.0, @7.0, @-4.0, @6.0]
NSLog( @"%7.1f", fn horner( coeffs, 3 ) )
coeffs = @[@4.0, @3.0, @2.0, @1.0]
NSLog( @"%7.1f", fn horner( coeffs, 10 ) )
coeffs = @[@1, @1, @0, @0, @1]
NSLog( @"%7.1f", fn horner( coeffs, 2 ) )
coeffs = @[@1.2, @2.3, @3.4, @4.5, @5.6]
NSLog( @"%7.1f", fn horner( coeffs, 8 ) )
coeffs = @[@1, @0, @1, @1, @1, @0, @0, @1]
NSLog( @"%7.1f", fn horner( coeffs, 2 ) )
HandleEvents</syntaxhighlight>
{{out}}
<pre>
128.0
1234.0
19.0
25478.8
157.0
</pre>
=={{header|GAP}}==
<
x := Indeterminate(Rationals, "x");
Line 655 ⟶ 1,187:
Horner(u, 3);
# 128</
=={{header|Go}}==
<
import "fmt"
Line 671 ⟶ 1,203:
func main() {
fmt.Println(horner(3, []int64{-19, 7, -4, 6}))
}</
Output:
<pre>
Line 679 ⟶ 1,211:
=={{header|Groovy}}==
Solution:
<
Test includes demonstration of [[currying]] to create polynomial functions of one variable from generic Horner's rule calculation. Also demonstrates constructing the derivative function for the given polynomial. And finally demonstrates in the Newton-Raphson method to find one of the polynomial's roots using the polynomial and derivative functions constructed earlier.
<
println (["p coefficients":coefficients])
Line 704 ⟶ 1,236:
def root = newtonRaphson(3g, testPoly, testDeriv)
println ([root:root.toString()[0..5], "p(root)":testPoly(root).toString()[0..5], "p'(root)":testDeriv(root).toString()[0..5]])</
Output:
Line 716 ⟶ 1,248:
=={{header|Haskell}}==
<
horner x = foldr (\a b -> a + b*x) 0
main = print $ horner 3 [-19, 7, -4, 6]</
=={{header|HicEst}}==
<
DATA coeffs/-19.0, 7.0, -4.0, 6.0/
Line 733 ⟶ 1,265:
Horner = x*Horner + c(i)
ENDDO
END</
=={{header|Icon}} and {{header|Unicon}}==
<syntaxhighlight lang="icon">
procedure poly_eval (x, coeffs)
accumulator := 0
Line 748 ⟶ 1,280:
write (poly_eval (3, [-19, 7, -4, 6]))
end
</syntaxhighlight>
=={{header|J}}==
'''Solution''':<
horner =: (#."0 _ |.)~ NB. Tacit
horner =:
horner =: 4 : ' (+ *&y)/x' NB. Alternate explicit (equivalent)
</syntaxhighlight>
'''Example''':<syntaxhighlight lang="j"> _19 7 _4 6 horner 3
128</syntaxhighlight>
'''Note:'''<br>
The primitive verb <code>p.</code> would normally be used to evaluate polynomials.
<
128</
=={{header|Java}}==
{{works with|Java|1.5+}}
<
import java.util.Collections;
import java.util.List;
Line 790 ⟶ 1,319:
return accumulator;
}
}</
Output:
<pre>128.0</pre>
Line 798 ⟶ 1,327:
{{trans|Haskell}}
<
return coeffs.reduceRight( function(acc, coeff) { return(acc * x + coeff) }, 0);
}
console.log(horner([-19,7,-4,6],3)); // ==> 128
</syntaxhighlight>
=={{header|jq}}==
<syntaxhighlight lang=jq>
# Input: an array of coefficients specifying the polynomial
# to be evaluated at $x, where .[0] is the constant
def horner($x):
. as $coefficients
| reduce range(length-1; -1; -1) as $i (0; . * $x + $coefficients[$i]);
# Example
[-19, 7, -4, 6] | horner(3)
</syntaxhighlight>
'''Invocation''': $JQ -n -f horner.jq
where $JQ is either jq or gojq
{{output}}
<pre>
128
</pre>
=={{header|Julia}}==
{{works with|Julia|1.x}}
'''Imperative''':
<syntaxhighlight lang="julia">function horner(coefs, x)
s = coefs[end] * one(x)
for k in length(coefs)-1:-1:1
end
return
end
@show horner([-19, 7, -4, 6], 3)</syntaxhighlight>
{{out}}
<pre>horner([-19, 7, -4, 6], 3) = 128</pre>
'''Functional''':
<
{{out}}
<pre>horner2([-19, 7, -4, 6], 3) = 128</pre>
'''Note''':
In Julia 1.4 or later one would normally use the built-in '''evalpoly''' function for this purpose:
<syntaxhighlight lang="julia">
@show evalpoly(3, [-19, 7, -4, 6]) </syntaxhighlight>
{{out}}
<pre>evalpoly(3, [-19, 7, -4, 6]) = 128</pre>
=={{header|K}}==
<syntaxhighlight lang="k">
horner:{y _sv|x}
horner[-19 7 -4 6;3]
128
</syntaxhighlight>
=={{header|Kotlin}}==
<
fun horner(coeffs: DoubleArray, x: Double): Double {
Line 843 ⟶ 1,406:
val coeffs = doubleArrayOf(-19.0, 7.0, -4.0, 6.0)
println(horner(coeffs, 3.0))
}</
{{out}}
Line 849 ⟶ 1,412:
128.0
</pre>
=={{header|Lambdatalk}}==
<syntaxhighlight lang="scheme">
{def horner
{def horner.r
{lambda {:p :x :r}
{if {A.empty? :p}
then :r
else {horner.r {A.rest :p} :x {+ {A.first :p} {* :x :r}}}}}}
{lambda {:p :x}
{horner.r {A.reverse :p} :x 0}}}
{horner {A.new -19 7 -4 6} 3}
-> 128
{def φ {/ {+ 1 {sqrt 5}} 2}} = 1.618033988749895
{horner {A.new -1 -1 1} φ}
-> 2.220446049250313e-16 ~ 0
</syntaxhighlight>
=={{header|Liberty BASIC}}==
<
coefficients$ = "-19 7 -4 6" ' list coefficients of all x^0..x^n in order
x = 3
Line 870 ⟶ 1,453:
horner = accumulator
end function
</
=={{header|Logo}}==
<
if empty? :coeffs [output 0]
output (first :coeffs) + (:x * horner :x bf :coeffs)
end
show horner 3 [-19 7 -4 6] ; 128</
=={{header|Lua}}==
<
local res = 0
for i = #coeff, 1, -1 do
Line 891 ⟶ 1,474:
x = 3
coefficients = { -19, 7, -4, 6 }
print( horners_rule( coefficients, x ) )</
=={{header|Maple}}==
<syntaxhighlight lang="maple">
applyhorner:=(L::list,x)->foldl((s,t)->s*x+t,op(ListTools:-Reverse(L))):
Line 901 ⟶ 1,483:
applyhorner([-19,7,-4,6],3);
</syntaxhighlight>
Output:
<pre>
Line 910 ⟶ 1,492:
=={{header|Mathematica}} / {{header|Wolfram Language}}==
<
Horner[{6, -4, 7, -19}, x]
-> -19 + x (7 + x (-4 + 6 x))
-19 + x (7 + x (-4 + 6 x)) /. x -> 3
-> 128</
=={{header|MATLAB}}==
<
accumulator = 0;
Line 926 ⟶ 1,508:
end
end</
Output:
<
ans =
128</
Matlab also has a built-in function "polyval" which uses Horner's Method to evaluate polynomials. The list of coefficients is in descending order of power, where as to task spec specifies ascending order.
<
ans =
128</
=={{header|Maxima}}==
<
horner(5*x^3+2*x+1);
x*(5*x^2+2)+1
Line 985 ⟶ 1,567:
poleval([0, 0, 0, 0, 1], x);
x^4</
=={{header|Mercury}}==
<
:- module horner.
:- interface.
Line 1,002 ⟶ 1,584:
horner(X, Cs) = list.foldr((func(C, Acc) = Acc * X + C), Cs, 0).
</syntaxhighlight>
=={{header|МК-61/52}}==
<syntaxhighlight lang="text">ИП0 1 + П0
ИПE ИПD * КИП0 + ПE
ИП0 1 - x=0 04
ИПE С/П</
''Input:'' Р1:РС - coefficients, Р0 - number of the coefficients, РD - ''x''.
=={{header|Modula-2}}==
<syntaxhighlight lang="modula2">MODULE Horner;
FROM RealStr IMPORT RealToStr;
FROM Terminal IMPORT WriteString,WriteLn,ReadChar;
PROCEDURE Horner(coeff : ARRAY OF REAL; x : REAL) : REAL;
VAR
ans : REAL;
i : CARDINAL;
BEGIN
ans := 0.0;
FOR i:=HIGH(coeff) TO 0 BY -1 DO
ans := (ans * x) + coeff[i];
END;
RETURN ans
END Horner;
TYPE A = ARRAY[0..3] OF REAL;
VAR
buf : ARRAY[0..63] OF CHAR;
coeff : A;
ans : REAL;
BEGIN
coeff := A{-19.0, 7.0, -4.0, 6.0};
ans := Horner(coeff, 3.0);
RealToStr(ans, buf);
WriteString(buf);
WriteLn;
ReadChar
END Horner.</syntaxhighlight>
=={{header|NetRexx}}==
<
options replace format comments java crossref savelog symbols nobinary
Line 1,024 ⟶ 1,637:
End
Say r
Say 6*x**3-4*x**2+7*x-19</
'''Output:'''
<pre>128
Line 1,030 ⟶ 1,643:
=={{header|Nim}}==
<syntaxhighlight lang="nim"># You can also just use `reversed` proc from stdlib `algorithm` module
iterator reversed[T](x: openArray[T]): T =
for i in countdown(x.high, x.low):
yield x[i]
proc horner[T](coeffs: openArray[T], x: T): int =
for c in reversed(coeffs):
result = result * x + c
echo horner([-19, 7, -4, 6], 3)</
=={{header|Oberon-2}}==
{{works with|oo2c}}
<
MODULE HornerRule;
IMPORT
Line 1,071 ⟶ 1,685:
Out.Int(Eval(coefs^,4,3),0);Out.Ln
END HornerRule.
</syntaxhighlight>
{{out}}
<pre>
128
</pre>
=={{header|Objeck}}==
<syntaxhighlight lang="objeck">
class Horner {
function : Main(args : String[]) ~ Nil {
coeffs := Collection.FloatVector->New();
coeffs->AddBack(-19.0);
coeffs->AddBack(7.0);
coeffs->AddBack(-4.0);
coeffs->AddBack(6.0);
PolyEval(coeffs, 3)->PrintLine();
}
function : PolyEval(coefficients : Collection.FloatVector , x : Float) ~ Float {
accumulator := coefficients->Get(coefficients->Size() - 1);
for(i := coefficients->Size() - 2; i > -1; i -= 1;) {
accumulator := (accumulator * x) + coefficients->Get(i);
};
return accumulator;
}
}
</syntaxhighlight>
=={{header|Objective-C}}==
{{works with|Mac OS X|10.6+}} Using blocks
<
typedef double (^mfunc)(double, double);
Line 1,120 ⟶ 1,757:
}
return 0;
}</
=={{header|OCaml}}==
<
List.fold_left (fun acc coef -> acc * x + coef) 0 (List.rev coeffs) ;;
val horner : int list -> int -> int = <fun>
Line 1,153 ⟶ 1,767:
# let coeffs = [-19; 7; -4; 6] in
horner coeffs 3 ;;
- : int = 128</
It's also possible to do fold_right instead of reversing and doing fold_left; but fold_right is not tail-recursive.
=={{header|Octave}}==
<
r = 0.0;
for i = length(a):-1:1
Line 1,164 ⟶ 1,778:
endfunction
horner([-19, 7, -4, 6], 3)</
=={{header|ooRexx}}==
<
* 04.03.2014 Walter Pachl
*--------------------------------------------------------------------*/
Line 1,178 ⟶ 1,792:
End
Say r
Say 6*x**3-4*x**2+7*x-19</
'''Output:'''
<pre>128
128</pre>
=={{header|Oz}}==
<
fun {Horner Coeffs X}
{FoldL1 {Reverse Coeffs}
Line 1,196 ⟶ 1,810:
end
in
{Show {Horner [~19 7 ~4 6] 3}}</
=={{header|PARI/GP}}==
Also note that Pari has a polynomial type. Evaluating these is as simple as <code>subst(P,variable(P),x)</code>.
<
my(s=0);
forstep(i=#v,1,-1,s=s*x+v[i]);
s
};</
=={{header|Pascal}}==
<
function horner(a: array of double; x: double): double;
Line 1,224 ⟶ 1,838:
write ('Horner calculated polynomial of 6*x^3 - 4*x^2 + 7*x - 19 for x = 3: ');
writeln (horner (poly, 3.0):8:4);
end.</
Output:
<pre>Horner calculated polynomial of 6*x^3 - 4*x^2 + 7*x - 19 for x = 3: 128.0000
Line 1,230 ⟶ 1,844:
=={{header|Perl}}==
<
use strict;
use warnings;
Line 1,243 ⟶ 1,857:
my @coeff = (-19.0, 7, -4, 6);
my $x = 3;
say horner @coeff, $x;</
===<!-- Perl -->Functional version===
<
use List::Util qw(reduce);
Line 1,256 ⟶ 1,870:
my @coeff = (-19.0, 7, -4, 6);
my $x = 3;
print horner(\@coeff, $x), "\n";</
===<!-- Perl -->Recursive version===
<
my ($coeff, $x) = @_;
@$coeff and
Line 1,265 ⟶ 1,879:
}
print horner( [ -19, 7, -4, 6 ], 3 );</
=={{header|Phix}}==
<!--<syntaxhighlight lang="phix">(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">horner</span><span style="color: #0000FF;">(</span><span style="color: #004080;">atom</span> <span style="color: #000000;">x</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">sequence</span> <span style="color: #000000;">coeff</span><span style="color: #0000FF;">)</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: #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;">coeff</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: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">res</span><span style="color: #0000FF;">*</span><span style="color: #000000;">x</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">coeff</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</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: #0000FF;">?</span><span style="color: #000000;">horner</span><span style="color: #0000FF;">(</span><span style="color: #000000;">3</span><span style="color: #0000FF;">,{-</span><span style="color: #000000;">19</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">7</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">4</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">6</span><span style="color: #0000FF;">})</span>
<!--</syntaxhighlight>-->
{{out}}
<pre>
Line 1,319 ⟶ 1,900:
=={{header|PHP}}==
<
function horner($coeff, $x) {
$result = 0;
Line 1,330 ⟶ 1,911:
$x = 3;
echo horner($coeff, $x), "\n";
?></
===Functional version===
{{works with|PHP|5.3+}}
<
function horner($coeff, $x) {
return array_reduce(array_reverse($coeff), function ($a, $b) use ($x) { return $a * $x + $b; }, 0);
Line 1,342 ⟶ 1,923:
$x = 3;
echo horner($coeff, $x), "\n";
?></
=={{header|Picat}}==
===Recursion===
<syntaxhighlight lang="picat">horner([],_X,0).
horner([H|T],X,V) :-
horner(T,X,V1),
V = V1 * X + H.</syntaxhighlight>
===Iterative===
<syntaxhighlight lang="picat">horner2(Coeff, X, V) =>
Acc = 0,
foreach(I in Coeff.length..-1..1)
Acc := Acc*X + Coeff[I]
end,
V = Acc.</syntaxhighlight>
===Functional approach===
<syntaxhighlight lang="picat">h3(X,A,B) = A+B*X.
horner3(Coeff, X) = fold($h3(X),0,Coeff.reverse()).</syntaxhighlight>
===Test===
<syntaxhighlight lang="picat">go =>
horner([-19, 7, -4, 6], 3, V),
println(V),
horner2([-19, 7, -4, 6], 3, V2),
println(V2),
V3 = horner3([-19, 7, -4, 6], 3),
println(V3),
nl.</syntaxhighlight>
{{out}}
<pre>128
128
128</pre>
=={{header|PicoLisp}}==
<
(let Res 0
(for C (reverse Coeffs)
(setq Res (+ C (* X Res))) ) ) )</
<
-> 128</
=={{header|PL/I}}==
<syntaxhighlight lang="pl/i">
declare (i, n) fixed binary, (x, value) float; /* 11 May 2010 */
get (x);
Line 1,366 ⟶ 1,983:
put (value);
end;
</syntaxhighlight>
=={{header|Potion}}==
<
result = 0
coef reverse each (a) :
Line 1,377 ⟶ 1,994:
.
horner(3, (-19, 7, -4, 6)) print</
=={{header|PowerShell}}==
{{works with|PowerShell|4.0}}
<syntaxhighlight lang="powershell">
function horner($coefficients, $x) {
$accumulator = 0
Line 1,392 ⟶ 2,009:
$x = 3
horner $coefficients $x
</syntaxhighlight>
<b>Output:</b>
<pre>
Line 1,400 ⟶ 2,017:
=={{header|Prolog}}==
Tested with SWI-Prolog. Works with other dialects.
<
horner([H|T], X, V) :-
horner(T, X, V1),
V is V1 * X + H.
</syntaxhighlight>
Output :
<
V = 128.</
===Functional approach===
Works with SWI-Prolog and module lambda, written by <b>Ulrich Neumerkel</b> found there http://www.complang.tuwien.ac.at/ulrich/Prolog-inedit/lambda.pl
<
Line 1,424 ⟶ 2,041:
f_horner(L, V, R) :-
foldr(\X^Y^Z^(Z is X * V + Y), 0, L, R).
</syntaxhighlight>
===Functional syntax (Ciao)===
Works with Ciao (https://github.com/ciao-lang/ciao) and the fsyntax package:
<syntaxhighlight lang="prolog">
:- module(_, [horner/3], [fsyntax, hiord]).
:- use_module(library(hiordlib)).
horner(L, X) := ~foldr((''(H,V0,V) :- V is V0*X + H), L, 0).
</syntaxhighlight>
=={{header|PureBasic}}==
<
Define result
ForEach Coefficients()
Line 1,441 ⟶ 2,058:
Next
ProcedureReturn result
EndProcedure</
'''Implemented as
<
AddElement(a()): a()= 6
AddElement(a()): a()= -4
AddElement(a()): a()= 7
AddElement(a()): a()=-19
Debug Horner(a(),3)</
'''Outputs
128
=={{header|Python}}==
<
acc = 0
for c in reversed(coeffs):
Line 1,461 ⟶ 2,078:
>>> horner( (-19, 7, -4, 6), 3)
128</
===Functional version===
<
except: pass
Line 1,471 ⟶ 2,088:
>>> horner( (-19, 7, -4, 6), 3)
128</
==={{libheader|
<
>>> numpy.polynomial.polynomial.polyval(3, (-19, 7, -4, 6))
128.0</
=={{header|R}}==
Procedural style:
<
y <- 0
for(c in rev(a)) {
Line 1,488 ⟶ 2,105:
}
cat(horner(c(-19, 7, -4, 6), 3), "\n")</
Functional style:
<
Reduce(v, right=T, f=function(a, b) {
b * x + a
})
}</
{{out}}
<pre>
Line 1,505 ⟶ 2,122:
Translated from Haskell
<
#lang racket
(define (horner x l)
Line 1,512 ⟶ 2,129:
(horner 3 '(-19 7 -4 6))
</syntaxhighlight>
=={{header|Raku}}==
(formerly Perl 6)
<syntaxhighlight lang="raku" line>sub horner ( @coeffs, $x ) {
@coeffs.reverse.reduce: { $^a * $x + $^b };
}
say horner( [ -19, 7, -4, 6 ], 3 );</syntaxhighlight>
A recursive version would spare us the need for reversing the list of coefficients. However, special care must be taken in order to write it, because the way Raku implements lists is not optimized for this kind of treatment. [[Lisp]]-style lists are, and fortunately it is possible to emulate them with [http://doc.raku.org/type/Pair Pairs] and the reduction meta-operator:
<syntaxhighlight lang="raku" line>multi horner(Numeric $c, $) { $c }
multi horner(Pair $c, $x) {
$c.key + $x * horner( $c.value, $x )
}
say horner( [=>](-19, 7, -4, 6 ), 3 );</syntaxhighlight>
We can also use the composition operator:
<syntaxhighlight lang="raku" line>sub horner ( @coeffs, $x ) {
([o] map { $_ + $x * * }, @coeffs)(0);
}
say horner( [ -19, 7, -4, 6 ], 3 );</syntaxhighlight>
{{out}}
<pre>128</pre>
One advantage of using the composition operator is that it allows for the use of an infinite list of coefficients.
<syntaxhighlight lang="raku" line>sub horner ( @coeffs, $x ) {
map { .(0) }, [\o] map { $_ + $x * * }, @coeffs;
}
say horner( [ 1 X/ (1, |[\*] 1 .. *) ], i*pi )[20];
</syntaxhighlight>
{{out}}
<pre>-0.999999999924349-5.28918515954219e-10i</pre>
=={{header|Rascal}}==
<
public int horners_rule(list[int] coefficients, int x){
Line 1,522 ⟶ 2,176:
acc = acc * x + i;}
return acc;
}</
A neater and shorter solution using a reducer:
<
Output:
<
int: 128
rascal>horners_rule2([-19, 7, -4, 6], 3)
int: 128</
=={{header|REBOL}}==
<
horner: func [coeffs x] [
Line 1,544 ⟶ 2,198:
]
print horner [-19 7 -4 6] 3</
=={{header|REXX}}==
===version 1===
<
numeric digits 30 /*use extra numeric precision. */
parse arg x poly /*get value of X and the coefficients. */
Line 1,566 ⟶ 2,220:
end /*j*/
say /*display a blank line for readability.*/
say ' answer = ' a /*stick a fork in it, we're all done. */</
'''output''' when the following is used for input: <tt> 3 -19 7 -4 6 </tt>
<pre>
Line 1,577 ⟶ 2,231:
===version 2===
<
* 27.07.2012 Walter Pachl
* coefficients reversed to descending order of power
Line 1,621 ⟶ 2,275:
Say ' equation = ' equ
Say ' '
Say ' result = ' a</
{{out}}
<pre> x = 3
Line 1,630 ⟶ 2,284:
=={{header|Ring}}==
<
coefficients = [-19, 7, -4, 6]
see "x = 3" + nl +
Line 1,643 ⟶ 2,297:
next
return w
</syntaxhighlight>
Output:
<pre>
Line 1,659 ⟶ 2,313:
This said, solution to the problem is
<syntaxhighlight lang="rlab">
>> a = [6, -4, 7, -19]
6 -4 7 -19
Line 1,667 ⟶ 2,321:
128
</syntaxhighlight>
=={{header|RPL}}==
===Translation of the algorithm===
Following the pseudocode given [https://web.physics.utah.edu/~detar/lessons/c++/array/node2.html here] to the letter:
≪ OVER DUP SIZE GET → a x0 p
≪ a SIZE 1 - 1 '''FOR''' j
'a(j)+x0*p' EVAL 'p' STO -1 '''STEP'''
p
≫ ≫ ‘'''HORNR'''’ STO
===Idiomatic one-liner===
Reducing the loop to its simplest form: one memory call, one multiplication and one addition.
≪ → x0 ≪ LIST→ 2 SWAP '''START''' x0 * + '''NEXT''' ≫ ≫ ‘'''HORNR'''’ STO
{{in}}
<pre>
{ -19 7 -4 6 } 3 HORNR
</pre>
{{out}}
<pre>
1: 128
</pre>
=={{header|Ruby}}==
<
coeffs.reverse.inject(0) {|acc, coeff| acc * x + coeff}
end
p horner([-19, 7, -4, 6], 3) # ==> 128</
=={{header|Run BASIC}}==
<
x = 3
print horner(coef$,x) '128
Line 1,722 ⟶ 2,367:
next
horner = accum
end function</
=={{header|Rust}}==
<syntaxhighlight lang="rust">fn horner(v: &[f64], x: f64) -> f64 {
v.iter().rev().fold(0.0, |acc, coeff| acc*x + coeff)
}
fn main() {
let v = [-19., 7., -4., 6.];
println!("result: {}", horner(&v, 3.0));
}</syntaxhighlight>
A generic version that works with any number type and much more. So much more, it's hard to imagine what that may be useful for.
<syntaxhighlight lang="rust">extern crate num; // 0.2.0
use num::Zero;
use std::ops::{Add, Mul};
fn horner<Arr, Arg, Out>(v: &[Arr], x: Arg) -> Out
where
Arr: Clone,
Arg: Clone,
Out: Zero + Mul<Arg, Output = Out> + Add<Arr, Output = Out>,
{
v.iter()
.rev()
.fold(Zero::zero(), |acc, coeff| acc * x.clone() + coeff.clone())
}
fn main() {
let v = [-19., 7., -4., 6.];
let output: f64 = horner(&v, 3.0);
println!("result: {}", output);
}</syntaxhighlight>
=={{header|Sather}}==
<
action(s, e, x:FLT):FLT is
Line 1,739 ⟶ 2,416:
#OUT + horner(|-19.0, 7.0, -4.0, 6.0|, 3.0) + "\n";
end;
end;</
=={{header|Scala}}==
<
coeffs.reverse.foldLeft(0.0){(a,c)=> a*x+c}
</syntaxhighlight>
<
println(horner(coeffs, 3))
-> 128.0
</syntaxhighlight>
=={{header|Scheme}}==
{{Works with|Scheme|R<math>^5</math>RS}}
<
(define (*horner lst x acc)
(if (null? lst)
Line 1,760 ⟶ 2,437:
(display (horner (list -19 7 -4 6) 3))
(newline)</
Output:
<syntaxhighlight lang="text">128</
=={{header|Seed7}}==
<
include "float.s7i";
Line 1,786 ⟶ 2,463:
begin
writeln(horner(coeffs, 3.0) digits 1);
end func;</
Output:
Line 1,795 ⟶ 2,472:
=={{header|Sidef}}==
Functional:
<
coeff.reverse.reduce { |a,b| a*x + b };
}
say horner([-19, 7, -4, 6], 3); # => 128</
Recursive:
<
(coeff.len > 0) \
: 0
}
say horner([-19, 7, -4, 6], 3)
=={{header|Smalltalk}}==
{{works with|GNU Smalltalk}}
<
horner: aValue [
^ self reverse inject: 0 into: [:acc :c | acc * aValue + c].
Line 1,817 ⟶ 2,495:
].
(#(-19 7 -4 6) asOrderedCollection horner: 3) displayNl.</
=={{header|Standard ML}}==
<
fun horner coeffList x = foldr (fn (a, b) => a + b * x) (0.0) coeffList</
=={{header|Swift}}==
<
return reduce(lazy(coefs).reverse(), 0) { $0 * x + $1 }
}
println(horner([-19, 7, -4, 6], 3))</
{{out}}
<pre>128.0</pre>
=={{header|Tcl}}==
<
proc horner {coeffs x} {
set y 0
Line 1,840 ⟶ 2,518:
}
return $y
}</
Demonstrating:
<
Output:
<pre>128</pre>
Line 1,850 ⟶ 2,528:
Note: this function, "Horner", gets its coefficients as a ParamArray which has no specified length. This array collect all arguments after the first one(s). This means you must specify x first, then the coefficients.
<syntaxhighlight lang="vba">
Public Function Horner(x, ParamArray coeff())
Dim result As Double
Line 1,863 ⟶ 2,541:
Horner = result
End Function
</syntaxhighlight>
Output:
Line 1,870 ⟶ 2,548:
128
</pre>
=={{header|VBScript}}==
<syntaxhighlight lang="vb">
Function horners_rule(coefficients,x)
accumulator = 0
For i = UBound(coefficients) To 0 Step -1
accumulator = (accumulator * x) + coefficients(i)
Next
horners_rule = accumulator
End Function
WScript.StdOut.WriteLine horners_rule(Array(-19,7,-4,6),3)
</syntaxhighlight>
{{Out}}
<pre>128</pre>
=={{header|Visual Basic .NET}}==
{{trans|C#}}
<syntaxhighlight lang="vbnet">Module Module1
Function Horner(coefficients As Double(), variable As Double) As Double
Return coefficients.Reverse().Aggregate(Function(acc, coeff) acc * variable + coeff)
End Function
Sub Main()
Console.WriteLine(Horner({-19.0, 7.0, -4.0, 6.0}, 3.0))
End Sub
End Module</syntaxhighlight>
{{out}}
<pre>128</pre>
=={{header|Visual FoxPro}}==
===Coefficients in ascending order.===
<
LOCAL x As Double
LOCAL ARRAY aCoeffs[1]
Line 1,893 ⟶ 2,603:
RETURN s
ENDFUNC
</syntaxhighlight>
===Coefficients in descending order.===
<
LOCAL x As Double
LOCAL ARRAY aCoeffs[1]
Line 1,915 ⟶ 2,625:
RETURN s
ENDFUNC
</syntaxhighlight>
=={{header|
<syntaxhighlight lang="v (vlang)">fn horner(x i64, c []i64) i64 {
mut acc := i64(0)
for i := c.len - 1; i >= 0; i-- {
acc = acc*x + c[i]
}
return acc
}
fn main() {
println(horner(3, [i64(-19), 7, -4, 6]))
}</syntaxhighlight>
{{out}}
<
128
</pre>
=={{
<syntaxhighlight lang="wren">var horner = Fn.new { |x, c|
var count = c.count
if (count == 0) return 0
return (count-1..0).reduce(0) { |acc, index| acc*x + c[index] }
}
System.print(horner.call(3, [-19, 7, -4, 6]))</syntaxhighlight>
{{out}}
<pre>
128
</pre>
=={{header|XPL0}}==
<
func Horner(X, N, C); \Return value of polynomial in X
Line 1,945 ⟶ 2,671:
];
IntOut(0, Horner(3, 4, [-19, 7, -4, 6]));</
Output:
Line 1,953 ⟶ 2,679:
=={{header|zkl}}==
<
{ coeffs.reverse().reduce('wrap(a,coeff){ a*x + coeff },0.0) }</
{{out}}
<pre>
|