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		y = Abs(y)
    28	
    29		yfr, yexp := Frexp(y)
    30		r := x
    31		if x < 0 {
    32			r = -x
    33		}
    34	
    35		for r >= y {
    36			rfr, rexp := Frexp(r)
    37			if rfr < yfr {
    38				rexp = rexp - 1
    39			}
    40			r = r - Ldexp(y, rexp-yexp)
    41		}
    42		if x < 0 {
    43			r = -r
    44		}
    45		return r
    46	}
    47	

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