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fix miller-rabin, safe primes

Doug Coleman 2009-05-06 12:21:30 -05:00
parent 9b5933d97c
commit a2a5129a84
1 changed files with 11 additions and 7 deletions
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18
basis/math/miller-rabin/miller-rabin.factor
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@ -1,7 +1,7 @@
! Copyright (C) 2008 Doug Coleman. ! Copyright (C) 2008 Doug Coleman.
! See http://factorcode.org/license.txt for BSD license. ! See http://factorcode.org/license.txt for BSD license.
USING: combinators kernel locals math math.functions math.ranges USING: combinators kernel locals math math.functions math.ranges
random sequences sets combinators.short-circuit ; random sequences sets combinators.short-circuit math.bitwise ;
IN: math.miller-rabin IN: math.miller-rabin
<PRIVATE <PRIVATE
@ -14,15 +14,17 @@ TUPLE: positive-even-expected n ;
n 1 - :> n-1 n 1 - :> n-1
n-1 factor-2s :> s :> r n-1 factor-2s :> s :> r
0 :> a! 0 :> a!
t :> prime?!
trials [ trials [
drop
n 1 - [1,b] random a! n 1 - [1,b] random a!
a s n ^mod 1 = [ a s n ^mod 1 = [
f
] [
r iota [ r iota [
2^ s * a swap n ^mod n - -1 = 2^ s * a swap n ^mod n - -1 =
] any? not [ f prime?! trials + ] when ] any? not
] unless drop ] if
] each prime? ; ] any? not ;
PRIVATE> PRIVATE>
@ -83,7 +85,6 @@ ERROR: too-few-primes ;
1 + 6 divisor? ; 1 + 6 divisor? ;
: next-safe-prime-candidate ( n -- candidate ) : next-safe-prime-candidate ( n -- candidate )
1 - 2/
next-prime dup safe-prime-candidate? next-prime dup safe-prime-candidate?
[ next-safe-prime-candidate ] unless ; [ next-safe-prime-candidate ] unless ;
@ -101,5 +102,8 @@ PRIVATE>
dup miller-rabin dup miller-rabin
[ nip ] [ drop next-safe-prime ] if ; [ nip ] [ drop next-safe-prime ] if ;
: random-bits* ( numbits -- n )
[ random-bits ] keep set-bit ;
: random-safe-prime ( numbits -- p ) : random-safe-prime ( numbits -- p )
random-bits next-safe-prime ; 1- random-bits* next-safe-prime ;