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/* $OpenBSD: n_fmod.c,v 1.6 2008/06/21 08:26:19 martynas Exp $ */
/* $NetBSD: n_fmod.c,v 1.1 1995/10/10 23:36:49 ragge Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static char sccsid[] = "@(#)fmod.c 8.1 (Berkeley) 6/4/93";
#endif /* not lint */
#include "math.h"
#include "mathimpl.h"
/* fmod.c
*
* SYNOPSIS
*
* #include <math.h>
* double fmod(double x, double y)
*
* DESCRIPTION
*
* The fmod function computes the floating-point remainder of x/y.
*
* RETURNS
*
* The fmod function returns the value x-i*y, for some integer i
* such that, if y is nonzero, the result has the same sign as x and
* magnitude less than the magnitude of y.
*
* On a VAX or CCI,
*
* fmod(x,0) traps/faults on floating-point divided-by-zero.
*
* On IEEE-754 conforming machines with "isnan()" primitive,
*
* fmod(x,0), fmod(INF,y) are invalid operations and NaN is returned.
*
*/
double
fmod(double x, double y)
{
int ir,iy;
double r,w;
if (y == (double)0 || isnan(y) || !finite(x))
return (x*y)/(x*y);
r = fabs(x);
y = fabs(y);
(void)frexp(y,&iy);
while (r >= y) {
(void)frexp(r,&ir);
w = ldexp(y,ir-iy);
r -= w <= r ? w : w*(double)0.5;
}
return x >= (double)0 ? r : -r;
}
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