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Diffstat (limited to 'sysdeps/generic/fmod.c')
| -rw-r--r-- | sysdeps/generic/fmod.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/sysdeps/generic/fmod.c b/sysdeps/generic/fmod.c new file mode 100644 index 0000000..09a31b2 --- /dev/null +++ b/sysdeps/generic/fmod.c @@ -0,0 +1,155 @@ +/* + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. 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 */ + +/* 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. + * + */ +#if !defined(vax) && !defined(tahoe) +extern int isnan(),finite(); +#endif /* !defined(vax) && !defined(tahoe) */ +extern double frexp(),ldexp(),fabs(); + +#ifdef TEST_FMOD +static double +_fmod(x,y) +#else /* TEST_FMOD */ +double +fmod(x,y) +#endif /* TEST_FMOD */ +double x,y; +{ + int ir,iy; + double r,w; + + if (y == (double)0 +#if !defined(vax) && !defined(tahoe) /* per "fmod" manual entry, SunOS 4.0 */ + || isnan(y) || !finite(x) +#endif /* !defined(vax) && !defined(tahoe) */ + ) + 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; +} + +#ifdef TEST_FMOD +extern long random(); +extern double fmod(); + +#define NTEST 10000 +#define NCASES 3 + +static int nfail = 0; + +static void +doit(x,y) +double x,y; +{ + double ro = fmod(x,y),rn = _fmod(x,y); + if (ro != rn) { + (void)printf(" x = 0x%08.8x %08.8x (%24.16e)\n",x,x); + (void)printf(" y = 0x%08.8x %08.8x (%24.16e)\n",y,y); + (void)printf(" fmod = 0x%08.8x %08.8x (%24.16e)\n",ro,ro); + (void)printf("_fmod = 0x%08.8x %08.8x (%24.16e)\n",rn,rn); + (void)printf("\n"); + } +} + +main() +{ + register int i,cases; + double x,y; + + srandom(12345); + for (i = 0; i < NTEST; i++) { + x = (double)random(); + y = (double)random(); + for (cases = 0; cases < NCASES; cases++) { + switch (cases) { + case 0: + break; + case 1: + y = (double)1/y; break; + case 2: + x = (double)1/x; break; + default: + abort(); break; + } + doit(x,y); + doit(x,-y); + doit(-x,y); + doit(-x,-y); + } + } + if (nfail) + (void)printf("Number of failures: %d (out of a total of %d)\n", + nfail,NTEST*NCASES*4); + else + (void)printf("No discrepancies were found\n"); + exit(0); +} +#endif /* TEST_FMOD */ |