52 lines
918 B
Go
52 lines
918 B
Go
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// Copyright 2009-2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package math
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/*
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Floating-point mod function.
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*/
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// Mod returns the floating-point remainder of x/y.
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// The magnitude of the result is less than y and its
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// sign agrees with that of x.
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//
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// Special cases are:
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// Mod(±Inf, y) = NaN
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// Mod(NaN, y) = NaN
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// Mod(x, 0) = NaN
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// Mod(x, ±Inf) = x
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// Mod(x, NaN) = NaN
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func Mod(x, y float64) float64 {
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return libc_fmod(x, y)
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}
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//extern fmod
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func libc_fmod(float64, float64) float64
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func mod(x, y float64) float64 {
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if y == 0 || IsInf(x, 0) || IsNaN(x) || IsNaN(y) {
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return NaN()
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}
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y = Abs(y)
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yfr, yexp := Frexp(y)
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r := x
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if x < 0 {
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r = -x
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}
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for r >= y {
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rfr, rexp := Frexp(r)
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if rfr < yfr {
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rexp = rexp - 1
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}
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r = r - Ldexp(y, rexp-yexp)
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}
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if x < 0 {
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r = -r
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}
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return r
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}
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