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# Source file src/math/frexp.go

## Documentation: math

```     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  //	Frexp(±0) = ±0, 0
14  //	Frexp(±Inf) = ±Inf, 0
15  //	Frexp(NaN) = NaN, 0
16  func Frexp(f float64) (frac float64, exp int) {
17  	if haveArchFrexp {
18  		return archFrexp(f)
19  	}
20  	return frexp(f)
21  }
22
23  func frexp(f float64) (frac float64, exp int) {
24  	// special cases
25  	switch {
26  	case f == 0:
27  		return f, 0 // correctly return -0
28  	case IsInf(f, 0) || IsNaN(f):
29  		return f, 0
30  	}
31  	f, exp = normalize(f)
32  	x := Float64bits(f)
33  	exp += int((x>>shift)&mask) - bias + 1
34  	x &^= mask << shift
35  	x |= (-1 + bias) << shift
36  	frac = Float64frombits(x)
37  	return
38  }
39
```

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