summaryrefslogtreecommitdiff
path: root/libgo/go/math/modf.go
blob: 315174b70144ab31494dbf6c8e585835b11722b9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package math

// Modf returns integer and fractional floating-point numbers
// that sum to f.  Both values have the same sign as f.
//
// Special cases are:
//	Modf(+Inf) = +Inf, NaN
//	Modf(-Inf) = -Inf, NaN
//	Modf(NaN) = NaN, NaN
func Modf(f float64) (int float64, frac float64) {
	if f < 1 {
		if f < 0 {
			int, frac = Modf(-f)
			return -int, -frac
		}
		return 0, f
	}

	x := Float64bits(f)
	e := uint(x>>shift)&mask - bias

	// Keep the top 12+e bits, the integer part; clear the rest.
	if e < 64-12 {
		x &^= 1<<(64-12-e) - 1
	}
	int = Float64frombits(x)
	frac = f - int
	return
}