49 lines
973 B
Go
49 lines
973 B
Go
|
// Copyright 2009-2010 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
|
||
|
|
|
||
|
|
|
||
|
|
/*
|
||
|
|
Floating-point mod function.
|
||
|
|
*/
|
||
|
|
|
||
|
|
// Fmod returns the floating-point remainder of x/y.
|
||
|
|
// The magnitude of the result is less than y and its
|
||
|
|
// sign agrees with that of x.
|
||
|
|
//
|
||
|
|
// Special cases are:
|
||
|
|
// if x is not finite, Fmod returns NaN
|
||
|
|
// if y is 0 or NaN, Fmod returns NaN
|
||
|
|
func Fmod(x, y float64) float64 {
|
||
|
|
// TODO(rsc): Remove manual inlining of IsNaN, IsInf
|
||
|
|
// when compiler does it for us.
|
||
|
|
if y == 0 || x > MaxFloat64 || x < -MaxFloat64 || x != x || y != y { // y == 0 || IsInf(x, 0) || IsNaN(x) || IsNan(y)
|
||
|
|
return NaN()
|
||
|
|
}
|
||
|
|
if y < 0 {
|
||
|
|
y = -y
|
||
|
|
}
|
||
|
|
|
||
|
|
yfr, yexp := Frexp(y)
|
||
|
|
sign := false
|
||
|
|
r := x
|
||
|
|
if x < 0 {
|
||
|
|
r = -x
|
||
|
|
sign = true
|
||
|
|
}
|
||
|
|
|
||
|
|
for r >= y {
|
||
|
|
rfr, rexp := Frexp(r)
|
||
|
|
if rfr < yfr {
|
||
|
|
rexp = rexp - 1
|
||
|
|
}
|
||
|
|
r = r - Ldexp(y, rexp-yexp)
|
||
|
|
}
|
||
|
|
if sign {
|
||
|
|
r = -r
|
||
|
|
}
|
||
|
|
return r
|
||
|
|
}
|