Source file src/pkg/math/mod.go
1 // Copyright 2009-2010 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package math 6 7 /* 8 Floating-point mod function. 9 */ 10 11 // Mod returns the floating-point remainder of x/y. 12 // The magnitude of the result is less than y and its 13 // sign agrees with that of x. 14 // 15 // Special cases are: 16 // Mod(±Inf, y) = NaN 17 // Mod(NaN, y) = NaN 18 // Mod(x, 0) = NaN 19 // Mod(x, ±Inf) = x 20 // Mod(x, NaN) = NaN 21 func Mod(x, y float64) float64 22 23 func mod(x, y float64) float64 { 24 if y == 0 || IsInf(x, 0) || IsNaN(x) || IsNaN(y) { 25 return NaN() 26 } 27 if y < 0 { 28 y = -y 29 } 30 31 yfr, yexp := Frexp(y) 32 sign := false 33 r := x 34 if x < 0 { 35 r = -x 36 sign = true 37 } 38 39 for r >= y { 40 rfr, rexp := Frexp(r) 41 if rfr < yfr { 42 rexp = rexp - 1 43 } 44 r = r - Ldexp(y, rexp-yexp) 45 } 46 if sign { 47 r = -r 48 } 49 return r 50 }