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// 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.
*/
// Mod 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, Mod returns NaN
// if y is 0 or NaN, Mod returns NaN
func Mod(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
}
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