1 /* $OpenBSD: infinity.c,v 1.2 2004/01/16 19:34:37 miod Exp $ */
2 /*
3 * Written by Miodrag Vallat, 2004 - Public Domain
4 * Inspired from Perl's t/op/arith test #134
5 */
6
7 #include <math.h>
8 #include <signal.h>
9 #include <unistd.h>
10
11 void
sigfpe(int signum)12 sigfpe(int signum)
13 {
14 /* looks like we don't handle fp overflow correctly... */
15 _exit(1);
16 }
17
18 int
main(int argc,char * argv[])19 main(int argc, char *argv[])
20 {
21 int opt;
22 double d, two;
23 int i;
24 char method = 'a';
25
26 while ((opt = getopt(argc, argv, "amnp")) != -1)
27 method = (char)opt;
28
29 signal(SIGFPE, sigfpe);
30
31 switch (method) {
32 case 'a':
33 /* try to produce +Inf through addition */
34 d = 1.0;
35 for (i = 2000; i != 0; i--) {
36 d = d + d;
37 }
38 /* result should be _positive_ infinity */
39 if (!isinf(d) || copysign(1.0, d) < 0.0)
40 return (1);
41 break;
42 case 'm':
43 /* try to produce +Inf through multiplication */
44 d = 1.0;
45 two = 2.0;
46 for (i = 2000; i != 0; i--) {
47 d = d * two;
48 }
49 /* result should be _positive_ infinity */
50 if (!isinf(d) || copysign(1.0, d) < 0.0)
51 return (1);
52 break;
53 case 'n':
54 /* try to produce -Inf through subtraction */
55 d = -1.0;
56 for (i = 2000; i != 0; i--) {
57 d = d + d;
58 }
59 /* result should be _negative_ infinity */
60 if (!isinf(d) || copysign(1.0, d) > 0.0)
61 return (1);
62 break;
63 case 'p':
64 /* try to produce -Inf through multiplication */
65 d = -1.0;
66 two = 2.0;
67 for (i = 2000; i != 0; i--) {
68 d = d * two;
69 }
70 /* result should be _negative_ infinity */
71 if (!isinf(d) || copysign(1.0, d) > 0.0)
72 return (1);
73 break;
74 }
75
76 return (0);
77 }
78