// 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 { if haveArchMod { return archMod(x, y) } return mod(x, y) } 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 }