Source file src/pkg/math/fmod.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	// Fmod 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	//	if x is not finite, Fmod returns NaN
    17	//	if y is 0 or NaN, Fmod returns NaN
    18	func Fmod(x, y float64) float64 {
    19		// TODO(rsc): Remove manual inlining of IsNaN, IsInf
    20		// when compiler does it for us.
    21		if y == 0 || x > MaxFloat64 || x < -MaxFloat64 || x != x || y != y { // y == 0 || IsInf(x, 0) || IsNaN(x) || IsNan(y)
    22			return NaN()
    23		}
    24		if y < 0 {
    25			y = -y
    26		}
    27	
    28		yfr, yexp := Frexp(y)
    29		sign := false
    30		r := x
    31		if x < 0 {
    32			r = -x
    33			sign = true
    34		}
    35	
    36		for r >= y {
    37			rfr, rexp := Frexp(r)
    38			if rfr < yfr {
    39				rexp = rexp - 1
    40			}
    41			r = r - Ldexp(y, rexp-yexp)
    42		}
    43		if sign {
    44			r = -r
    45		}
    46		return r
    47	}
The Go Programming Language

Source file src/pkg/math/fmod.go
