Fractran: Difference between revisions

Programming note: extra blanks can be inserted in the fractions before and/or after the solidus ['''/'''].

===showing all terms===

</pre>

===showing powers of 2 terms===

Programming note: &nbsp; If the number of terms is a negative integer, then only powers of two are displayed.

<lang rexx>/*REXX pgm runs FRACTAN for a given set of fractions and from a given N.*/

numeric digits 1000 /*be able to handle larger nums. */

parse arg N terms fracs /*get optional arguments from CL.*/

if N=='' | N==',' then N=2 /*N specified? No, use default.*/

if terms==''|terms==',' then terms=100 /*TERMS specified? Use default.*/

if fracs='' then fracs= , /*any fractions specified? No···*/

'17/91, 78/85, 19/51, 23/38, 29/33, 77/29, 95/23, 77/19, 1/17, 11/13, 13/11, 15/14, 15/2, 55/1'

f=space(fracs,0) /* [↑] use default for fractions.*/

tell= terms>0 /*flag: show # or a power of 2.*/

do i=1 while f\==''; parse var f n.i '/' d.i ',' f

end /*i*/ /* [↑] parse all the fractions.*/

!.=0 /*default value for powers of 2.*/

if \tell then do p=0 until length(_)>100; _=2**p; !._=1; @._='2**'p

end /*p*/ /* [↑] build powers of 2 tables.*/

#=i-1 /*the number of fractions found. */

say # 'fractions:' fracs /*display # and actual fractions.*/

say 'N is starting at ' N /*display the starting number N.*/

if tell then say terms ' terms are being shown:' /*display hdr.*/

else say 'only powers of two are being shown:' /* " " */

do j=1 for abs(terms) /*perform loop once for each term*/

do k=1 for #; if N//d.k\==0 then iterate /*not an integer?*/

if tell then say right('term' j,35) '──► ' N /*display Nth term&N*/

else if !.N then say right('term' j,35) '──► ' N ' ' @.N

N = N * n.k % d.k /*calculate the next term (use %)*/

leave /*go start calculating next term.*/

end /*k*/ /* [↑] if integer, found a new N*/

end /*j*/

/*stick a fork in it, we're done.*/</lang>

'''output''' using the input of: &nbsp; <tt> , -1000000 </tt>

<pre>

14 fractions: 17/91, 78/85, 19/51, 23/38, 29/33, 77/29, 95/23, 77/19, 1/17, 11/13, 13/11, 15/14, 15/2, 55/1

N is starting at 2

only powers of two are being shown:

term 1 ──► 2 2**1

term 20 ──► 4 2**2

term 70 ──► 8 2**3

term 281 ──► 32 2**5

term 708 ──► 128 2**7

term 2364 ──► 2048 2**11

term 3877 ──► 8192 2**13

term 8069 ──► 131072 2**17

term 11320 ──► 524288 2**19

term 19202 ──► 8388608 2**23

term 36867 ──► 536870912 2**29

term 45552 ──► 2147483648 2**31

term 75225 ──► 137438953472 2**37

term 101113 ──► 2199023255552 2**41

term 117832 ──► 8796093022208 2**43

term 152026 ──► 140737488355328 2**47

term 215385 ──► 9007199254740992 2**53

term 293376 ──► 576460752303423488 2**59

term 327021 ──► 2305843009213693952 2**61

term 428554 ──► 147573952589676412928 2**67

term 507520 ──► 2361183241434822606848 2**71

term 555695 ──► 9444732965739290427392 2**73

term 700064 ──► 604462909807314587353088 2**79

term 808332 ──► 9671406556917033397649408 2**83

term 989527 ──► 618970019642690137449562112 2**89