Source file src/math/nextafter.go

Documentation: math

		 1  // Copyright 2010 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  // Nextafter32 returns the next representable float32 value after x towards y.
		 8  //
		 9  // Special cases are:
		10  //	Nextafter32(x, x)	 = x
		11  //	Nextafter32(NaN, y) = NaN
		12  //	Nextafter32(x, NaN) = NaN
		13  func Nextafter32(x, y float32) (r float32) {
		14  	switch {
		15  	case IsNaN(float64(x)) || IsNaN(float64(y)): // special case
		16  		r = float32(NaN())
		17  	case x == y:
		18  		r = x
		19  	case x == 0:
		20  		r = float32(Copysign(float64(Float32frombits(1)), float64(y)))
		21  	case (y > x) == (x > 0):
		22  		r = Float32frombits(Float32bits(x) + 1)
		23  	default:
		24  		r = Float32frombits(Float32bits(x) - 1)
		25  	}
		26  	return
		27  }
		28  
		29  // Nextafter returns the next representable float64 value after x towards y.
		30  //
		31  // Special cases are:
		32  //	Nextafter(x, x)	 = x
		33  //	Nextafter(NaN, y) = NaN
		34  //	Nextafter(x, NaN) = NaN
		35  func Nextafter(x, y float64) (r float64) {
		36  	switch {
		37  	case IsNaN(x) || IsNaN(y): // special case
		38  		r = NaN()
		39  	case x == y:
		40  		r = x
		41  	case x == 0:
		42  		r = Copysign(Float64frombits(1), y)
		43  	case (y > x) == (x > 0):
		44  		r = Float64frombits(Float64bits(x) + 1)
		45  	default:
		46  		r = Float64frombits(Float64bits(x) - 1)
		47  	}
		48  	return
		49  }
		50  

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