diff options
Diffstat (limited to 'libgo/go/math/frexp.go')
| -rw-r--r-- | libgo/go/math/frexp.go | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/libgo/go/math/frexp.go b/libgo/go/math/frexp.go index b63b508e600..867b78f3648 100644 --- a/libgo/go/math/frexp.go +++ b/libgo/go/math/frexp.go @@ -8,6 +8,11 @@ package math // and an integral power of two. // It returns frac and exp satisfying f == frac × 2**exp, // with the absolute value of frac in the interval [½, 1). +// +// Special cases are: +// Frexp(±0) = ±0, 0 +// Frexp(±Inf) = ±Inf, 0 +// Frexp(NaN) = NaN, 0 func Frexp(f float64) (frac float64, exp int) { // TODO(rsc): Remove manual inlining of IsNaN, IsInf // when compiler does it for us @@ -18,10 +23,11 @@ func Frexp(f float64) (frac float64, exp int) { case f < -MaxFloat64 || f > MaxFloat64 || f != f: // IsInf(f, 0) || IsNaN(f): return f, 0 } + f, exp = normalize(f) x := Float64bits(f) - exp = int((x>>shift)&mask) - bias + exp += int((x>>shift)&mask) - bias + 1 x &^= mask << shift - x |= bias << shift + x |= (-1 + bias) << shift frac = Float64frombits(x) return } |