53 lines
5.3 KiB
Rexx
53 lines
5.3 KiB
Rexx
/*REXX program converts an integer (or a range) ──► a Van der Corput number, */
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/*─────────────── in base 2, or optionally, any other base up to and including base 90.*/
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numeric digits 1000 /*handle almost anything the user wants*/
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parse arg a b r . /*obtain optional arguments from the CL*/
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if a=='' | a=="," then parse value 0 10 with a b /*Not specified? Then use the defaults*/
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if b=='' | b=="," then b=a /* " " " " " " */
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if r=='' | r=="," then r=2 /* " " " " " " */
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z= /*a placeholder for a list of numbers. */
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do j=a to b /*traipse through the range of integers*/
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_=VdC( abs(j), abs(r) ) /*convert the ABSolute value of integer*/
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_=substr('-', 2 + sign(j) )_ /*if needed, keep the leading - sign.*/
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if r>0 then say _ /*if positive base, then just show it. */
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else z=z _ /* ··· else append (build) a list. */
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end /*j*/
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if z\=='' then say strip(z) /*if a list is wanted, then display it.*/
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exit /*stick a fork in it, we're all done. */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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base: procedure; parse arg x, toB, inB /*get a number, toBase, and inBase. */
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/*╔══════════════════════════════════════════════════════════════════════════════════╗
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║ Input to this function: x (X is required and it must be an integer). ║
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║ toBase the base to convert X to (default=10). ║
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║ inBase the base X is expressed in (default=10). ║
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║ ║
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║ toBase & inBase have a limit of: 2 ──► 90 ║
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╚══════════════════════════════════════════════════════════════════════════════════╝*/
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@abc= 'abcdefghijklmnopqrstuvwxyz' /*the lowercase Latin alphabet letters.*/
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@abcU=@abc; upper @abcU /*go whole hog & extend with uppercase.*/
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@@@= 0123456789 || @abc || @abcU /*prefix them with the decimal digits. */
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@@@= @@@'<>[]{}()?~!@#$%^&*_+-=|\/;:`' /*add some special characters as well, */
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/*──those chars should all be viewable.*/
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numeric digits 1000 /*what the hey, support bigun' numbers.*/
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maxB=length(@@@) /*maximum base (radix) supported here. */
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if toB=='' then toB=10 /*if omitted, then assume default (10)*/
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if inB=='' then inB=10 /* " " " " " " */
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#=0 /* [↓] convert base inB X ──► base 10*/
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do j=1 for length(x) /*process each "numeral" in the string.*/
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_=substr(x, j, 1) /*pick off a "digit" (numeral) from X.*/
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v=pos(_, @@@) /*get the value of this "digit"/numeral*/
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if v==0 | v>inB then call erd /*is it an illegal "digit" (numeral) ? */
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#=# * inB + v - 1 /*construct new number, digit by digit.*/
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end /*j*/
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y= /* [↓] convert base 10 # ──► base toB.*/
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do while #>=toB /*deconstruct the new number (#). */
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y=substr(@@@, # // toB + 1, 1)y /* construct the output number, ··· */
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#=# % toB /* ··· and also whittle down #. */
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end /*while*/
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return substr(@@@, # + 1, 1)y /*return a constructed "numeric" string*/
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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erd: say 'the character ' v " isn't a legal numeral for base " inB'.'; exit 13
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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VdC: return '.'reverse(base(arg(1), arg(2))) /*convert the #, reverse the #, append.*/
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