1// Copyright 2009 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// Modf returns integer and fractional floating-point numbers
8// that sum to f. Both values have the same sign as f.
9//
10// Special cases are:
11//	Modf(±Inf) = ±Inf, NaN
12//	Modf(NaN) = NaN, NaN
13func Modf(f float64) (int float64, frac float64) {
14	return modf(f)
15}
16
17func modf(f float64) (int float64, frac float64) {
18	if f < 1 {
19		switch {
20		case f < 0:
21			int, frac = Modf(-f)
22			return -int, -frac
23		case f == 0:
24			return f, f // Return -0, -0 when f == -0
25		}
26		return 0, f
27	}
28
29	x := Float64bits(f)
30	e := uint(x>>shift)&mask - bias
31
32	// Keep the top 12+e bits, the integer part; clear the rest.
33	if e < 64-12 {
34		x &^= 1<<(64-12-e) - 1
35	}
36	int = Float64frombits(x)
37	frac = f - int
38	return
39}
40