http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48651
Jerry DeLisle <jvdelisle at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |thenlich at users dot
| |sourceforge.net
--- Comment #1 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> 2011-04-17
18:07:27 UTC ---
Well, this is not a libgfortran issue. I am not convinced it is actually a
problem either. The resulting value from printf swings to the other side for
double or long double.
#include <stdio.h>
int
main ()
{
float num = 0.9;
double dnum = 0.9;
long double ldnum = 0.0;
printf("%30.28f\n", num);
printf("%30.28lf\n", num);
printf("%30.28f\n", dnum);
printf("%30.28lf\n", dnum);
printf("%30.28f\n", ldnum);
printf("%30.28lf\n", ldnum);
}
Gives:
$ ./a.out
0.8999999761581420898437500000
0.8999999761581420898437500000
0.9000000000000000222044604925
0.9000000000000000222044604925
0.9000000000000000222044604925
0.9000000000000000222044604925
The result flips to the other side of .9 which is not necessarily wrong.
0.9 - 0.8999999761581420898437500000 = 2.384185791×10⁻⁸
0.9 - 0.9000000000000000222044604925 = −2.220446049×10⁻¹⁷
