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
5package 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
13func 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
35func 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