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small cleanup in miller-rabin

db4
Doug Coleman 2008-01-12 21:46:53 -10:00
parent 37544fe24e
commit f8a0d7403d
1 changed files with 2 additions and 7 deletions
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extra/math/miller-rabin/miller-rabin.factor
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@ -20,17 +20,12 @@ SYMBOL: trials
: random-bits ( m -- n ) 2^ random ; foldable : random-bits ( m -- n ) 2^ random ; foldable
: (factor-2s) ( s n -- s n )
dup even? [ -1 shift >r 1+ r> (factor-2s) ] when ;
: factor-2s ( n -- r s ) : factor-2s ( n -- r s )
#! factor an even number into 2 ^ s * m #! factor an even number into 2 ^ s * m
dup even? over 0 > and [ dup even? [ -1 shift >r 1+ r> factor-2s ] when ;
"input must be positive and even" throw
] unless 0 swap (factor-2s) ;
:: (miller-rabin) | n prime?! | :: (miller-rabin) | n prime?! |
n 1- factor-2s s set r set 0 n 1- factor-2s s set r set
trials get [ trials get [
n 1- [1,b] random a set n 1- [1,b] random a set
a get s get n ^mod 1 = [ a get s get n ^mod 1 = [