steve
/
factor
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Optimize primes-between 

Rather than having primes-between return a slice of primes-upto,
make primes-upto use primes-between.

Also, those two words cannot be marked as foldable as their
output is mutable.
db4
Samuel Tardieu 2008-12-28 11:43:13 +01:00
parent a843113326
commit ca0f3659e4
1 changed files with 7 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
extra/math/primes/primes.factor
View File

@ -1,7 +1,7 @@
! Copyright (C) 2007 Samuel Tardieu. ! Copyright (C) 2007 Samuel Tardieu.
! See http://factorcode.org/license.txt for BSD license. ! See http://factorcode.org/license.txt for BSD license.
USING: binary-search combinators kernel lists.lazy math math.functions USING: combinators kernel lists.lazy math math.functions
math.miller-rabin math.primes.erato math.ranges sequences ; math.miller-rabin math.order math.primes.erato math.ranges sequences ;
IN: math.primes IN: math.primes
<PRIVATE <PRIVATE
@ -28,15 +28,11 @@ PRIVATE>
: lprimes-from ( n -- list ) : lprimes-from ( n -- list )
dup 3 < [ drop lprimes ] [ 1- next-prime [ next-prime ] lfrom-by ] if ; dup 3 < [ drop lprimes ] [ 1- next-prime [ next-prime ] lfrom-by ] if ;
: primes-upto ( n -- seq )
dup 2 < [
drop V{ }
] [
3 swap 2 <range> [ prime? ] filter 2 prefix
] if ; foldable
: primes-between ( low high -- seq ) : primes-between ( low high -- seq )
primes-upto [ 1- next-prime ] dip [ dup 3 max dup even? [ 1 + ] when ] dip
[ natural-search drop ] [ length ] [ ] tri <slice> ; foldable 2 <range> [ prime? ] filter
swap 3 < [ 2 prefix ] when ;
: primes-upto ( n -- seq ) 2 swap primes-between ;
: coprime? ( a b -- ? ) gcd nip 1 = ; foldable : coprime? ( a b -- ? ) gcd nip 1 = ; foldable