156 lines
4.2 KiB
C
156 lines
4.2 KiB
C
/*
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* Copyright (c) 1989 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static char sccsid[] = "@(#)fmod.c 5.2 (Berkeley) 6/1/90";
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#endif /* not lint */
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/* fmod.c
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*
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* SYNOPSIS
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*
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* #include <math.h>
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* double fmod(double x, double y)
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*
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* DESCRIPTION
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*
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* The fmod function computes the floating-point remainder of x/y.
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*
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* RETURNS
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*
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* The fmod function returns the value x-i*y, for some integer i
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* such that, if y is nonzero, the result has the same sign as x and
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* magnitude less than the magnitude of y.
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*
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* On a VAX or CCI,
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*
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* fmod(x,0) traps/faults on floating-point divided-by-zero.
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*
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* On IEEE-754 conforming machines with "isnan()" primitive,
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*
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* fmod(x,0), fmod(INF,y) are invalid operations and NaN is returned.
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*
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*/
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#if !defined(vax) && !defined(tahoe)
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extern int isnan(),finite();
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#endif /* !defined(vax) && !defined(tahoe) */
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extern double frexp(),ldexp(),fabs();
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#ifdef TEST_FMOD
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static double
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_fmod(x,y)
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#else /* TEST_FMOD */
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double
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fmod(x,y)
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#endif /* TEST_FMOD */
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double x,y;
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{
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int ir,iy;
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double r,w;
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if (y == (double)0
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#if !defined(vax) && !defined(tahoe) /* per "fmod" manual entry, SunOS 4.0 */
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|| isnan(y) || !finite(x)
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#endif /* !defined(vax) && !defined(tahoe) */
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)
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return (x*y)/(x*y);
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r = fabs(x);
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y = fabs(y);
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(void)frexp(y,&iy);
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while (r >= y) {
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(void)frexp(r,&ir);
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w = ldexp(y,ir-iy);
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r -= w <= r ? w : w*(double)0.5;
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}
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return x >= (double)0 ? r : -r;
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}
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#ifdef TEST_FMOD
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extern long random();
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extern double fmod();
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#define NTEST 10000
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#define NCASES 3
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static int nfail = 0;
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static void
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doit(x,y)
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double x,y;
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{
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double ro = fmod(x,y),rn = _fmod(x,y);
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if (ro != rn) {
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(void)printf(" x = 0x%08.8x %08.8x (%24.16e)\n",x,x);
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(void)printf(" y = 0x%08.8x %08.8x (%24.16e)\n",y,y);
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(void)printf(" fmod = 0x%08.8x %08.8x (%24.16e)\n",ro,ro);
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(void)printf("_fmod = 0x%08.8x %08.8x (%24.16e)\n",rn,rn);
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(void)printf("\n");
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}
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}
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main()
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{
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register int i,cases;
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double x,y;
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srandom(12345);
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for (i = 0; i < NTEST; i++) {
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x = (double)random();
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y = (double)random();
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for (cases = 0; cases < NCASES; cases++) {
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switch (cases) {
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case 0:
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break;
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case 1:
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y = (double)1/y; break;
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case 2:
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x = (double)1/x; break;
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default:
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abort(); break;
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}
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doit(x,y);
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doit(x,-y);
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doit(-x,y);
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doit(-x,-y);
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}
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}
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if (nfail)
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(void)printf("Number of failures: %d (out of a total of %d)\n",
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nfail,NTEST*NCASES*4);
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else
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(void)printf("No discrepancies were found\n");
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exit(0);
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}
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#endif /* TEST_FMOD */
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