// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package math

// Logb returns the binary exponent of x.
//
// Special cases are:
//
//	Logb(±Inf) = +Inf
//	Logb(0) = -Inf
//	Logb(NaN) = NaN
func Logb(x float64) float64 {
	// special cases
	switch {
	case x == 0:
		return Inf(-1)
	case IsInf(x, 0):
		return Inf(1)
	case IsNaN(x):