t19.c revision 1.4 
1/*	$OpenBSD: t19.c,v 1.4 2017/11/29 14:31:50 otto Exp $	*/
2
3/*
4 * Copyright (c) 2012 Otto Moerbeek <otto@drijf.net>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18#include <float.h>
19#include <math.h>
20#include <stdio.h>
21
22int scale[] = { 1, 2, 3, 10, 15, 20, 30};
23long double num[] = {-10, -M_PI, -3, -2, -1, -0.5, -0.01, 0, 0.01,
24  0.5, 1, 2, 3, M_PI, 10};
25
26struct func {const char *name; long double (*f)(long double);};
27
28struct func funcs[] = { {"s", sinl},
29			{"c", cosl},
30			{"e", expl},
31			{"l", logl},
32			{"a", atanl}
33};
34
35#define nitems(_a)      (sizeof((_a)) / sizeof((_a)[0]))
36
37int
38main(void)
39{
40	int ret, si, ni, fi;
41	int status = 0;
42
43	for (si = 0; si < nitems(scale); si++) {
44		for (ni = 0; ni < nitems(num); ni++) {
45			for (fi = 0; fi < nitems(funcs); fi++) {
46				char cmd[100];
47				FILE *fp;
48				long double v, d1, d2, diff, prec;
49
50				v = num[ni];
51				if (v == 0.0 && funcs[fi].f == logl)
52					continue;
53				snprintf(cmd, sizeof(cmd),
54				    "bc -l -e scale=%d -e '%s(%.19Lf)' -equit",
55				    scale[si], funcs[fi].name, v);
56				fp = popen(cmd, "r");
57				ret = fscanf(fp, "%Lf", &d1);
58				pclose(fp);
59				d2 = funcs[fi].f(v);
60				diff = fabsl(d1 - d2);
61				prec = powl(10.0L, (long double)-scale[si]);
62				if (prec < LDBL_EPSILON)
63					prec = LDBL_EPSILON;
64				prec *= 2;
65				/* XXX cheating ? */
66				if (funcs[fi].f == logl)
67					prec *= 4;
68				else if (funcs[fi].f == expl)
69					prec *= 8;
70				if (diff > prec) {
71					printf("%s %d %Le %Le %Le %Le %Le\n",
72					    funcs[fi].name, scale[si],
73					    v, d1, d2, diff, prec);
74					status = 1;
75				}
76
77			}
78		}
79	}
80	return status;
81}
82