math.primes.solovay-strassen: adding Solovay-Strassen primality test.

extra/math/primes/solovay-strassen/authors.txt

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+John Benediktsson

extra/math/primes/solovay-strassen/solovay-strassen-tests.factor

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+USING: kernel math.primes sequences tools.test ;
+IN: math.primes.solovay-strassen
+
+{ t } [
+    100,000 iota [ solovay-strassen ] filter
+    100,000 primes-upto =
+] unit-test

extra/math/primes/solovay-strassen/solovay-strassen.factor

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+! Copyright (C) 2014 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+
+USING: combinators kernel locals math math.extras
+math.extras.private math.functions math.ranges random sequences ;
+
+IN: math.primes.solovay-strassen
+
+<PRIVATE
+
+:: (solovay-strassen) ( n numtrials -- ? )
+    numtrials iota [
+        drop
+        n 1 - [1,b) random :> a
+        a n fast-gcd 1 > [ t ] [
+            a n jacobi n mod'
+            a n 1 - 2 /i n ^mod = not
+        ] if
+    ] any? not ;
+
+PRIVATE>
+
+: solovay-strassen* ( n numtrials -- ? )
+    {
+        { [ over 1 <= ] [ 2drop f ] }
+        { [ over even? ] [ drop 2 = ] }
+        [ (solovay-strassen) ]
+    } cond ;
+
+: solovay-strassen ( n -- ? ) 32 solovay-strassen* ;