43 lines
1021 B
Factor
43 lines
1021 B
Factor
! Copyright (C) 2007 Samuel Tardieu.
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! See http://factorcode.org/license.txt for BSD license.
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USING: arrays kernel lists math math.primes namespaces make
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sequences ;
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IN: math.primes.factors
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<PRIVATE
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: (factor) ( n d -- n' )
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2dup mod zero? [ [ / ] keep dup , (factor) ] [ drop ] if ;
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: (count) ( n d -- n' )
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[ (factor) ] { } make
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[ [ first ] keep length 2array , ] unless-empty ;
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: (unique) ( n d -- n' )
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[ (factor) ] { } make
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[ first , ] unless-empty ;
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: (factors) ( quot list n -- )
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dup 1 > [ swap uncons swap >r pick call r> swap (factors) ] [ 3drop ] if ;
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: (decompose) ( n quot -- seq )
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[ lprimes rot (factors) ] { } make ;
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PRIVATE>
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: factors ( n -- seq )
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[ (factor) ] (decompose) ; foldable
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: group-factors ( n -- seq )
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[ (count) ] (decompose) ; foldable
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: unique-factors ( n -- seq )
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[ (unique) ] (decompose) ; foldable
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: totient ( n -- t )
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dup 2 < [
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drop 0
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] [
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dup unique-factors dup 1 [ 1- * ] reduce swap product / *
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] if ; foldable
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