38 lines
918 B
Factor
38 lines
918 B
Factor
! Copyright (C) 2010 John Benediktsson.
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! See http://factorcode.org/license.txt for BSD license
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USING: combinators kernel locals math math.functions ;
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IN: math.approx
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<PRIVATE
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:: (simplest) ( n d n' d' -- val ) ! assumes 0 < n/d < n'/d'
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n d /mod :> ( q r )
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n' d' /mod :> ( q' r' )
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{
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{ [ r zero? ] [ q ] }
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{ [ q q' = not ] [ q 1 + ] }
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[
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d' r' d r (simplest) >fraction :> ( n'' d'' )
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q n'' * d'' + n'' /
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]
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} cond ;
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:: simplest ( x y -- val )
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{
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{ [ x y > ] [ y x simplest ] }
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{ [ x y = ] [ x ] }
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{ [ x 0 > ] [ x y [ >fraction ] bi@ (simplest) ] }
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{ [ y 0 < ] [ y x [ neg >fraction ] bi@ (simplest) neg ] }
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[ 0 ]
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} cond ;
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: check-float ( x -- x )
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dup float? [ "can't be floats" throw ] when ;
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PRIVATE>
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: approximate ( x epsilon -- y )
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[ check-float ] bi@ [ - ] [ + ] 2bi simplest ;
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