Factorial: Difference between revisions
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(→Soda: Tail recursive) |
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=={{header|Scheme}}== |
=={{header|Scheme}}== |
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===Recursive=== |
===Recursive=== |
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<syntaxhighlight lang="scheme"> |
<syntaxhighlight lang="scheme"> |
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(define (factorial n) |
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(if (<= n 0) |
(if (<= n 0) |
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1 |
1 |
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(* n (factorial (- n 1))))) |
(* n (factorial (- n 1))))) |
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</syntaxhighlight> |
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The following is tail-recursive, so it is effectively iterative: |
The following is tail-recursive, so it is effectively iterative: |
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<syntaxhighlight lang="scheme"> |
<syntaxhighlight lang="scheme"> |
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(define (factorial n) |
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(let loop ((i 1) |
(let loop ((i 1) |
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(accum 1)) |
(accum 1)) |
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(if (> i n) |
(if (> i n) |
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accum |
accum |
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(loop (+ i 1) (* accum i))))) |
(loop (+ i 1) (* accum i))))) |
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</syntaxhighlight> |
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===Iterative=== |
===Iterative=== |
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<syntaxhighlight lang="scheme"> |
<syntaxhighlight lang="scheme"> |
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(define (factorial n) |
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(do ((i 1 (+ i 1)) |
(do ((i 1 (+ i 1)) |
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(accum 1 (* accum i))) |
(accum 1 (* accum i))) |
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((> i n) accum))) |
((> i n) accum))) |
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</syntaxhighlight> |
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===Folding=== |
===Folding=== |
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<syntaxhighlight lang="scheme"> |
<syntaxhighlight lang="scheme"> |
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;Using a generator and a function that apply generated values to a function taking two arguments |
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;A generator knows commands 'next? and 'next |
;A generator knows commands 'next? and 'next |
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(factorial 8) |
(factorial 8) |
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;40320 |
;40320 |
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</syntaxhighlight> |
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=={{header|Scilab}}== |
=={{header|Scilab}}== |
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