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package math32
const (
uvnan = 0x7FE00000
uvinf = 0x7F800000
uvone = 0x3f800000
uvneginf = 0xFF800000
mask = 0xFF
shift = 32 - 8 - 1
bias = 127
signMask = 1 << 31
fracMask = 1<<shift - 1
)
// Inf returns positive infinity if sign >= 0, negative infinity if sign < 0.
func Inf(sign int) float32 {
var v uint32
if sign >= 0 {
v = uvinf
} else {
v = uvneginf
}
return Float32frombits(v)
}
// NaN returns an IEEE 754 ``not-a-number'' value.
func NaN() float32 { return Float32frombits(uvnan) }
// IsNaN reports whether f is an IEEE 754 ``not-a-number'' value.
func IsNaN(f float32) (is bool) {
// IEEE 754 says that only NaNs satisfy f != f.
// To avoid the floating-point hardware, could use:
// x := Float32bits(f)
// return uint32(x>>shift)&mask == mask && x != uvinf && x != uvneginf
return f != f
}
// IsInf reports whether f is an infinity, according to sign.
// If sign > 0, IsInf reports whether f is positive infinity.
// If sign < 0, IsInf reports whether f is negative infinity.
// If sign == 0, IsInf reports whether f is either infinity.
func IsInf(f float32, sign int) bool {
// Test for infinity by comparing against maximum float.
// To avoid the floating-point hardware, could use:
// x := Float32bits(f)
// return sign >= 0 && x == uvinf || sign <= 0 && x == uvneginf
return sign >= 0 && f > MaxFloat32 || sign <= 0 && f < -MaxFloat32
}
// normalize returns a normal number y and exponent exp
// satisfying x == y × 2**exp. It assumes x is finite and non-zero.
func normalize(x float32) (y float32, exp int) {
const SmallestNormal = 1.1754943508222875079687365e-38 // 2**-(127 - 1)
if Abs(x) < SmallestNormal {
return x * (1 << shift), -shift
}
return x, 0
}
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