diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/pkg/math/bits.go | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/src/pkg/math/bits.go b/src/pkg/math/bits.go index 65eabfd60..9f93a192b 100644 --- a/src/pkg/math/bits.go +++ b/src/pkg/math/bits.go @@ -29,8 +29,11 @@ func NaN() float64 { return Float64frombits(uvnan) } // IsNaN returns whether f is an IEEE 754 ``not-a-number'' value. func IsNaN(f float64) (is bool) { - x := Float64bits(f) - return uint32(x>>shift)&mask == mask && x != uvinf && x != uvneginf + // IEEE 754 says that only NaNs satisfy f != f. + // To avoid the floating-point hardware, could use: + // x := Float64bits(f); + // return uint32(x>>shift)&mask == mask && x != uvinf && x != uvneginf + return f != f } // IsInf returns whether f is an infinity, according to sign. @@ -38,8 +41,11 @@ func IsNaN(f float64) (is bool) { // If sign < 0, IsInf returns whether f is negative infinity. // If sign == 0, IsInf returns whether f is either infinity. func IsInf(f float64, sign int) bool { - x := Float64bits(f) - return sign >= 0 && x == uvinf || sign <= 0 && x == uvneginf + // Test for infinity by comparing against maximum float. + // To avoid the floating-point hardware, could use: + // x := Float64bits(f); + // return sign >= 0 && x == uvinf || sign <= 0 && x == uvneginf; + return sign >= 0 && f > MaxFloat64 || sign <= 0 && f < -MaxFloat64 } // Frexp breaks f into a normalized fraction |