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/*
* gnu25.c
*
* This was originally reported as a bug in the Sun C compiler in
* Sun-Spots, by ihnp4!stcvax!stc-auts!kak, but he forgot to declare
* double sqrt(). However, the code generated for the initialization
* by gcc-1.19 plus a fix, reuses fp0 for both arguments of the divide.
* oops! the result is always 1!
John Gilmore, 16April88
*
* showbug
* compile: cc showbug.c -o showbug -lm
*/
double sqrt();
compare(a, b)
double a, b;
{
if (a != b) return 1; /* Not computed the same */
if (a > 0.014) return 1; /* Wrong answer */
if (a < 0.012) return 1; /* Wrong answer */
return 0;
}
main()
{
float mean = 0.035000;
int samples = 200;
{
double sigma = sqrt( (mean*(1 - mean))/ samples);
if (compare(sigma,
sqrt((mean*(1 - mean))/ samples ))) {
printf("sigma = sqrt( (%f)/%d) ",
(mean*(1 - mean)), samples );
printf("= sqrt( %f ) ",
(mean*(1 - mean))/ samples );
printf("= %f ",
sqrt((mean*(1 - mean))/ samples ));
printf("= %f (!)\n", sigma );
} else {
printf("Test passed\n");
}
}
}
/* We'd like to link with -lm, but "runt" doesnt do this. */
double sqrt(x) double x;
{
/* Quick fakery. */
if (x > .000165 && x < .00017) /* arg is right */
return .0129951914; /* Right result */
return 0; /* CHeap imitation sqrt routine */
}
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