Floating point comparisons with NaN values produce wrong results

[Stephen L Moshier]

Your fixed test case works properly on x86 and sparc.
Now we need a PA expert to look into the problem.

>Floating point comparisons (< <= > >=) with NaN values produce wrong
>results in
>  GNU CPP version 2.95 19990718 (prerelease)
>  hppa2.0-hp-hpux10.20



On Mon, 6 Sep 1999, Olli Saarela wrote:

> Stephen L Moshier wrote:
> > 
> > > static const char double_q_nan_bytes_be[8] = {0x7f, 0xf8, 0, 0, 0, 0,
> > 0, 0};
> > 
> > > #define double_q_nan  (*(const double *)double_q_nan_bytes_be)
> > 
> > This is not valid C language.  You need to fix your test case.
> 
> A fixed version is included below. This doesn't affect the results, the
> inequality comparisons (< > <= >=) still give wrong results.
> 
> #include <stdio.h>
> #include <math.h>
> 
> union DoubleInit {
>   char   bytes[8];
>   double f;
> };
> 
> /* Quiet NaN : depends on byte order */
> 
> const union DoubleInit double_q_nan_bytes_le = {{0, 0, 0, 0, 0, 0, 0xf8,
> 0x7f}};
> const union DoubleInit double_q_nan_bytes_be = {{0x7f, 0xf8, 0, 0, 0, 0,
> 0, 0}};
> 
> #define double_q_nan  double_q_nan_bytes_be.f
> 
> void compare(double x, double y) {
>   printf("%10f <  %10f %s\n", x, y, (x <  y) ? "TRUE" : "FALSE");
>   printf("%10f <= %10f %s\n", x, y, (x <= y) ? "TRUE" : "FALSE");
>   printf("%10f >  %10f %s\n", x, y, (x >  y) ? "TRUE" : "FALSE");
>   printf("%10f >= %10f %s\n", x, y, (x >= y) ? "TRUE" : "FALSE");
>   printf("%10f == %10f %s\n", x, y, (x == y) ? "TRUE" : "FALSE");
>   printf("%10f != %10f %s\n", x, y, (x != y) ? "TRUE" : "FALSE");
>   printf("%10f == %10f %s\n", x, 0.0, (x == 0.0) ? "TRUE" : "FALSE");
>   printf("%10f != %10f %s\n", x, 0.0, (x != 0.0) ? "TRUE" : "FALSE");
>   printf("\n");
> }
> 
> int main(int argc, char *argv[]) {
>   compare(1.0, double_q_nan);
>   compare(double_q_nan, 1.0);
>   compare(double_q_nan, double_q_nan);
>   return 0;
> }
> 
> -- 
> Olli Saarela, KCL - The Finnish Pulp and Paper Research Institute
> Olli.Saarela@kcl.fi                tel. +358-9-4371538 (office)
> Tekniikantie 2, Espoo-Otaniemi     fax. +358-9-464305
> P.O. Box 70, FIN-02151 Espoo, Finland
>