| // 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: |
| // Mod(±Inf, y) = NaN |
| // Mod(NaN, y) = NaN |
| // Mod(x, 0) = NaN |
| // Mod(x, ±Inf) = x |
| // Mod(x, NaN) = NaN |
| func Mod(x, y float64) float64 { |
| return libc_fmod(x, y) |
| } |
| |
| //extern fmod |
| func libc_fmod(float64, float64) float64 |
| |
| func mod(x, y float64) float64 { |
| if y == 0 || IsInf(x, 0) || IsNaN(x) || IsNaN(y) { |
| return NaN() |
| } |
| y = Abs(y) |
| |
| yfr, yexp := Frexp(y) |
| r := x |
| if x < 0 { |
| r = -x |
| } |
| |
| for r >= y { |
| rfr, rexp := Frexp(r) |
| if rfr < yfr { |
| rexp = rexp - 1 |
| } |
| r = r - Ldexp(y, rexp-yexp) |
| } |
| if x < 0 { |
| r = -r |
| } |
| return r |
| } |