56 lines
1.3 KiB
Factor
56 lines
1.3 KiB
Factor
! Copyright (C) 2004, 2005 Slava Pestov.
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! See http://factorcode.org/license.txt for BSD license.
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IN: math
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USING: errors kernel math math-internals ;
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: exp >rect swap fexp swap polar> ; inline
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: log >polar swap flog swap rect> ; inline
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GENERIC: sqrt ( n -- n ) foldable
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M: complex sqrt >polar swap fsqrt swap 2 / polar> ;
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M: real sqrt dup 0 < [ neg fsqrt 0 swap rect> ] [ fsqrt ] if ;
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GENERIC: (^) ( z w -- z^w ) foldable
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: ^ ( z w -- z^w )
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over zero? [
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dup zero?
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[ 2drop 0.0/0.0 ] [ 0 < [ drop 1.0/0.0 ] when ] if
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] [
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(^)
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] if ; inline
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: ^mag ( w abs arg -- magnitude )
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>r >r >rect swap r> swap fpow r> rot * fexp / ; inline
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: ^theta ( w abs arg -- theta )
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>r >r >rect r> flog * swap r> * + ; inline
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M: number (^)
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swap >polar 3dup ^theta >r ^mag r> polar> ;
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: ^n ( z w -- z^w )
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{
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{ [ dup zero? ] [ 2drop 1 ] }
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{ [ dup 1 number= ] [ drop ] }
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{ [ t ] [ over sq over 2 /i ^n -rot 2 mod ^n * ] }
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} cond ; inline
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M: integer (^)
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dup 0 < [ neg ^n recip ] [ ^n ] if ;
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: power-of-2? ( n -- ? )
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dup 0 > [
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dup dup neg bitand =
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] [
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drop f
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] if ; foldable
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: log2 ( n -- b )
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{
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{ [ dup 0 <= ] [ "log2 expects positive inputs" throw ] }
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{ [ dup 1 = ] [ drop 0 ] }
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{ [ t ] [ -1 shift log2 1+ ] }
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} cond ; foldable
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