Source: ldexp.go in package math

Source File
	ldexp.go

Belonging Package
	math


package math

Ldexp is the inverse of Frexp. It returns frac × 2**exp. Special cases are: Ldexp(±0, exp) = ±0 Ldexp(±Inf, exp) = ±Inf Ldexp(NaN, exp) = NaN

func Ldexp(frac float64, exp int) float64

special cases

	switch {
	case frac == 0:
		return frac // correctly return -0
	case IsInf(frac, 0) || IsNaN(frac):
		return frac
	}
	frac, e := normalize(frac)
	exp += e
	x := Float64bits(frac)
	exp += int(x>>shift)&mask - bias
	if exp < -1075 {
		return Copysign(0, frac) // underflow
	}
	if exp > 1023 { // overflow
		if frac < 0 {
			return Inf(-1)
		}
		return Inf(1)
	}
	var m float64 = 1
	if exp < -1022 { // denormal
		exp += 53
		m = 1.0 / (1 << 53) // 2**-53
	}
	x &^= mask << shift
	x |= uint64(exp+bias) << shift
	return m * Float64frombits(x)


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