39 lines
1.0 KiB
Factor
39 lines
1.0 KiB
Factor
! Copyright (C) 2007 Samuel Tardieu.
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! See http://factorcode.org/license.txt for BSD license.
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USING: combinators kernel lists.lazy math math.functions
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math.miller-rabin math.order math.primes.erato math.ranges sequences ;
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IN: math.primes
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<PRIVATE
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: look-in-bitmap ( n -- ? ) >index 4999999 sieve nth ;
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: really-prime? ( n -- ? )
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dup 5000000 < [ look-in-bitmap ] [ miller-rabin ] if ; foldable
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PRIVATE>
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: prime? ( n -- ? )
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{
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{ [ dup 2 < ] [ drop f ] }
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{ [ dup even? ] [ 2 = ] }
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[ really-prime? ]
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} cond ; foldable
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: next-prime ( n -- p )
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next-odd [ dup really-prime? ] [ 2 + ] [ ] until ; foldable
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: lprimes ( -- list ) 2 [ next-prime ] lfrom-by ;
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: lprimes-from ( n -- list )
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dup 3 < [ drop lprimes ] [ 1- next-prime [ next-prime ] lfrom-by ] if ;
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: primes-between ( low high -- seq )
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[ dup 3 max dup even? [ 1 + ] when ] dip
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2 <range> [ prime? ] filter
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swap 3 < [ 2 prefix ] when ;
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: primes-upto ( n -- seq ) 2 swap primes-between ;
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: coprime? ( a b -- ? ) gcd nip 1 = ; foldable
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