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//
11//	Nextafter32(x, x)   = x
12//	Nextafter32(NaN, y) = NaN
13//	Nextafter32(x, NaN) = NaN
14func Nextafter32(x, y float32) (r float32) {
15	switch {
16	case IsNaN(float64(x)) || IsNaN(float64(y)): // special case
17		r = float32(NaN())
18	case x == y:
19		r = x
20	case x == 0:
21		r = float32(Copysign(float64(Float32frombits(1)), float64(y)))
22	case (y > x) == (x > 0):
23		r = Float32frombits(Float32bits(x) + 1)
24	default:
25		r = Float32frombits(Float32bits(x) - 1)
26	}
27	return
28}
29
30// Nextafter returns the next representable float64 value after x towards y.
31//
32// Special cases are:
33//
34//	Nextafter(x, x)   = x
35//	Nextafter(NaN, y) = NaN
36//	Nextafter(x, NaN) = NaN
37func Nextafter(x, y float64) (r float64) {
38	switch {
39	case IsNaN(x) || IsNaN(y): // special case
40		r = NaN()
41	case x == y:
42		r = x
43	case x == 0:
44		r = Copysign(Float64frombits(1), y)
45	case (y > x) == (x > 0):
46		r = Float64frombits(Float64bits(x) + 1)
47	default:
48		r = Float64frombits(Float64bits(x) - 1)
49	}
50	return
51}
52