diff options
Diffstat (limited to 'libgo/go/math/big/int.go')
| -rw-r--r-- | libgo/go/math/big/int.go | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/libgo/go/math/big/int.go b/libgo/go/math/big/int.go index 4bd7958ae504..95c0d58ee979 100644 --- a/libgo/go/math/big/int.go +++ b/libgo/go/math/big/int.go @@ -412,7 +412,7 @@ func (x *Int) Format(s fmt.State, ch rune) { if precisionSet { switch { case len(digits) < precision: - zeroes = precision - len(digits) // count of zero padding + zeroes = precision - len(digits) // count of zero padding case digits == "0" && precision == 0: return // print nothing if zero value (x == 0) and zero precision ("." or ".0") } @@ -561,19 +561,18 @@ func (x *Int) BitLen() int { return x.abs.bitLen() } -// Exp sets z = x**y mod m and returns z. If m is nil, z = x**y. +// Exp sets z = x**y mod |m| (i.e. the sign of m is ignored), and returns z. +// If y <= 0, the result is 1; if m == nil or m == 0, z = x**y. // See Knuth, volume 2, section 4.6.3. func (z *Int) Exp(x, y, m *Int) *Int { if y.neg || len(y.abs) == 0 { - neg := x.neg - z.SetInt64(1) - z.neg = neg - return z + return z.SetInt64(1) } + // y > 0 var mWords nat if m != nil { - mWords = m.abs + mWords = m.abs // m.abs may be nil for m == 0 } z.abs = z.abs.expNN(x.abs, y.abs, mWords) |