diff options
Diffstat (limited to 'src/pkg/math/frexp.go')
| -rw-r--r-- | src/pkg/math/frexp.go | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/src/pkg/math/frexp.go b/src/pkg/math/frexp.go index 203219c0d..867b78f36 100644 --- a/src/pkg/math/frexp.go +++ b/src/pkg/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 @@ -18,8 +23,9 @@ 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 + 1 + exp += int((x>>shift)&mask) - bias + 1 x &^= mask << shift x |= (-1 + bias) << shift frac = Float64frombits(x) |