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big: fix ProbablyPrime bug, comments

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(changes adopted from alc, agl)

R=agl1, agl
CC=golang-dev
https://golang.org/cl/181137
This commit is contained in:
Russ Cox 2010-01-05 16:49:05 -08:00
parent e032ab9dc8
commit cfbee34a27
3 changed files with 14 additions and 4 deletions
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2
src/pkg/big/int.go
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@ -356,7 +356,7 @@ func GcdInt(d, x, y, a, b *Int) {
// ProbablyPrime performs n Miller-Rabin tests to check whether z is prime.
// If it returns true, z is prime with probability 1 - 1/4^n.
// If it returns false, z is not prime.
func ProbablyPrime(z *Int, reps int) bool { return !z.neg && probablyPrime(z.abs, reps) }
func ProbablyPrime(z *Int, n int) bool { return !z.neg && probablyPrime(z.abs, n) }
// Rsh sets z = x >> s and returns z.

7
src/pkg/big/int_test.go
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@ -474,8 +474,15 @@ var primes = []string{
"5",
"7",
"11",
"13756265695458089029",
"13496181268022124907",
"10953742525620032441",
"17908251027575790097",
"98920366548084643601728869055592650835572950932266967461790948584315647051443",
"94560208308847015747498523884063394671606671904944666360068158221458669711639",
// http://primes.utm.edu/lists/small/small3.html
"449417999055441493994709297093108513015373787049558499205492347871729927573118262811508386655998299074566974373711472560655026288668094291699357843464363003144674940345912431129144354948751003607115263071543163",
"230975859993204150666423538988557839555560243929065415434980904258310530753006723857139742334640122533598517597674807096648905501653461687601339782814316124971547968912893214002992086353183070342498989426570593",

9
src/pkg/big/nat.go
View File

@ -596,6 +596,9 @@ func powersOfTwoDecompose(n []Word) (q []Word, k Word) {
// possible. n is the bit length of limit.
func randomN(z []Word, rand *rand.Rand, limit []Word, n int) []Word {
bitLengthOfMSW := uint(n % _W)
if bitLengthOfMSW == 0 {
bitLengthOfMSW = _W
}
mask := Word((1 << bitLengthOfMSW) - 1)
z = makeN(z, len(limit), false)
@ -616,7 +619,7 @@ func randomN(z []Word, rand *rand.Rand, limit []Word, n int) []Word {
}
}
return z
return normN(z)
}
@ -702,8 +705,8 @@ const (
var bigOne = []Word{1}
var bigTwo = []Word{2}
// ProbablyPrime performs n Miller-Rabin tests to check whether n is prime.
// If it returns true, n is prime with probability 1 - 1/4^n.
// ProbablyPrime performs reps Miller-Rabin tests to check whether n is prime.
// If it returns true, n is prime with probability 1 - 1/4^reps.
// If it returns false, n is not prime.
func probablyPrime(n []Word, reps int) bool {
if len(n) == 0 {