Source file src/math/frexp.go

Documentation: math

		 1  // Copyright 2009 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package math
		 6  
		 7  // Frexp breaks f into a normalized fraction
		 8  // and an integral power of two.
		 9  // It returns frac and exp satisfying f == frac × 2**exp,
		10  // with the absolute value of frac in the interval [½, 1).
		11  //
		12  // Special cases are:
		13  //	Frexp(±0) = ±0, 0
		14  //	Frexp(±Inf) = ±Inf, 0
		15  //	Frexp(NaN) = NaN, 0
		16  func Frexp(f float64) (frac float64, exp int) {
		17  	if haveArchFrexp {
		18  		return archFrexp(f)
		19  	}
		20  	return frexp(f)
		21  }
		22  
		23  func frexp(f float64) (frac float64, exp int) {
		24  	// special cases
		25  	switch {
		26  	case f == 0:
		27  		return f, 0 // correctly return -0
		28  	case IsInf(f, 0) || IsNaN(f):
		29  		return f, 0
		30  	}
		31  	f, exp = normalize(f)
		32  	x := Float64bits(f)
		33  	exp += int((x>>shift)&mask) - bias + 1
		34  	x &^= mask << shift
		35  	x |= (-1 + bias) << shift
		36  	frac = Float64frombits(x)
		37  	return
		38  }
		39  

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