diff options
Diffstat (limited to 'src/math/big/int_test.go')
-rw-r--r-- | src/math/big/int_test.go | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/src/math/big/int_test.go b/src/math/big/int_test.go index ec05fbb1c..6070cf325 100644 --- a/src/math/big/int_test.go +++ b/src/math/big/int_test.go @@ -1448,24 +1448,40 @@ func TestNot(t *testing.T) { var modInverseTests = []struct { element string - prime string + modulus string }{ - {"1", "7"}, - {"1", "13"}, + {"1234567", "458948883992"}, {"239487239847", "2410312426921032588552076022197566074856950548502459942654116941958108831682612228890093858261341614673227141477904012196503648957050582631942730706805009223062734745341073406696246014589361659774041027169249453200378729434170325843778659198143763193776859869524088940195577346119843545301547043747207749969763750084308926339295559968882457872412993810129130294592999947926365264059284647209730384947211681434464714438488520940127459844288859336526896320919633919"}, } func TestModInverse(t *testing.T) { - var element, prime Int + var element, modulus, gcd, inverse Int one := NewInt(1) for i, test := range modInverseTests { (&element).SetString(test.element, 10) - (&prime).SetString(test.prime, 10) - inverse := new(Int).ModInverse(&element, &prime) - inverse.Mul(inverse, &element) - inverse.Mod(inverse, &prime) - if inverse.Cmp(one) != 0 { - t.Errorf("#%d: failed (e·e^(-1)=%s)", i, inverse) + (&modulus).SetString(test.modulus, 10) + (&inverse).ModInverse(&element, &modulus) + (&inverse).Mul(&inverse, &element) + (&inverse).Mod(&inverse, &modulus) + if (&inverse).Cmp(one) != 0 { + t.Errorf("#%d: failed (e·e^(-1)=%s)", i, &inverse) + } + } + // exhaustive test for small values + for n := 2; n < 100; n++ { + (&modulus).SetInt64(int64(n)) + for x := 1; x < n; x++ { + (&element).SetInt64(int64(x)) + (&gcd).GCD(nil, nil, &element, &modulus) + if (&gcd).Cmp(one) != 0 { + continue + } + (&inverse).ModInverse(&element, &modulus) + (&inverse).Mul(&inverse, &element) + (&inverse).Mod(&inverse, &modulus) + if (&inverse).Cmp(one) != 0 { + t.Errorf("ModInverse(%d,%d)*%d%%%d=%d, not 1", &element, &modulus, &element, &modulus, &inverse) + } } } } |