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/* $OpenBSD: infinity.c,v 1.2 2004/01/16 19:34:37 miod Exp $ */
/*
* Written by Miodrag Vallat, 2004 - Public Domain
* Inspired from Perl's t/op/arith test #134
*/
#include <math.h>
#include <signal.h>
#include <unistd.h>
void
sigfpe(int signum)
{
/* looks like we don't handle fp overflow correctly... */
_exit(1);
}
int
main(int argc, char *argv[])
{
int opt;
double d, two;
int i;
char method = 'a';
while ((opt = getopt(argc, argv, "amnp")) != -1)
method = (char)opt;
signal(SIGFPE, sigfpe);
switch (method) {
case 'a':
/* try to produce +Inf through addition */
d = 1.0;
for (i = 2000; i != 0; i--) {
d = d + d;
}
/* result should be _positive_ infinity */
if (!isinf(d) || copysign(1.0, d) < 0.0)
return (1);
break;
case 'm':
/* try to produce +Inf through multiplication */
d = 1.0;
two = 2.0;
for (i = 2000; i != 0; i--) {
d = d * two;
}
/* result should be _positive_ infinity */
if (!isinf(d) || copysign(1.0, d) < 0.0)
return (1);
break;
case 'n':
/* try to produce -Inf through subtraction */
d = -1.0;
for (i = 2000; i != 0; i--) {
d = d + d;
}
/* result should be _negative_ infinity */
if (!isinf(d) || copysign(1.0, d) > 0.0)
return (1);
break;
case 'p':
/* try to produce -Inf through multiplication */
d = -1.0;
two = 2.0;
for (i = 2000; i != 0; i--) {
d = d * two;
}
/* result should be _negative_ infinity */
if (!isinf(d) || copysign(1.0, d) > 0.0)
return (1);
break;
}
return (0);
}
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