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other algorithms use factor-2s, put it back to normal

db4
Doug Coleman 2008-01-13 07:51:46 -10:00
parent 37cde9e234
commit 0613d01fcc
1 changed files with 11 additions and 4 deletions
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extra/math/miller-rabin/miller-rabin.factor
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@ -20,12 +20,19 @@ SYMBOL: trials
: random-bits ( m -- n ) 2^ random ; foldable : random-bits ( m -- n ) 2^ random ; foldable
: factor-2s ( zero n -- r s ) TUPLE: positive-even-expected n ;
#! factor an even number into 2 ^ s * m
dup even? [ -1 shift >r 1+ r> factor-2s ] when ; : (factor-2s) ( r s -- r s )
dup even? [ -1 shift >r 1+ r> (factor-2s) ] when ;
: factor-2s ( n -- r s )
#! factor an even number into s * 2 ^ r
dup even? over 0 > and [
positive-even-expected construct-boa throw
] unless 0 swap (factor-2s) ;
:: (miller-rabin) | n prime?! | :: (miller-rabin) | n prime?! |
0 n 1- factor-2s s set r set 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 = [