Source file src/math/frexp.go

```     1  // Copyright 2009 The Go Authors. All rights reserved.
2  // Use of this source code is governed by a BSD-style
4
5  package math
6
7  // Frexp breaks f into a normalized fraction
8  // and an integral power of two.
9  // It returns frac and exp satisfying f == frac × 2**exp,
10  // with the absolute value of frac in the interval [½, 1).
11  //
12  // Special cases are:
13  //
14  //	Frexp(±0) = ±0, 0
15  //	Frexp(±Inf) = ±Inf, 0
16  //	Frexp(NaN) = NaN, 0
17  func Frexp(f float64) (frac float64, exp int) {
18  	if haveArchFrexp {
19  		return archFrexp(f)
20  	}
21  	return frexp(f)
22  }
23
24  func frexp(f float64) (frac float64, exp int) {
25  	// special cases
26  	switch {
27  	case f == 0:
28  		return f, 0 // correctly return -0
29  	case IsInf(f, 0) || IsNaN(f):
30  		return f, 0
31  	}
32  	f, exp = normalize(f)
33  	x := Float64bits(f)
34  	exp += int((x>>shift)&mask) - bias + 1
35  	x &^= mask << shift
36  	x |= (-1 + bias) << shift
37  	frac = Float64frombits(x)
38  	return
39  }
40
```

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