# Source file src/math/nextafter.go

```     1  // Copyright 2010 The Go Authors. All rights reserved.
2  // Use of this source code is governed by a BSD-style
4
5  package 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
14  func 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
37  func 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
```

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