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
