Re: asinh() gives NaN on Linux/x86/glibc with optimization on

[hjl at lucon dot org (H.J. Lu)]

> 
> H.J. Lu <hjl@lucon.org> writes:
> >
> >> 
> >> On RedHat Linux 5.2 (using glibc 2.0.7) for x86, asinh() returns NaN
> >> for negative arguments if optimizations are on. The error does not
> >> occur if optimizations are turned off. I'm not sure where the problem
> >> is--egcs or glibc. Using libc5 seems to solve the problem, but so does
> >> dropping back to gcc 2.7.2.
> >
> >Do you have a testcase?
> 
> Sure.
> 
> #include <stdio.h>
> #include <math.h>
> 
> main() {
> 
>   double ha;
> 
>   printf("Input argument for asinh: ");
>   scanf("%lf", &ha);
>   printf("asinh(%f)=%f\n", ha, asinh(ha));
>   exit(0);
> }
> 
> The program works correctly for positive arguments. Negative results
> (I tried -100, -50, -10, -5) all return NaN.
> 

# gcc -v
Reading specs from /usr/lib/gcc-lib/i586-pc-linux/egcs-2.91.60/specs
gcc version egcs-2.91.60 19981201 (egcs-1.1.1 release)
# gcc -O6 x.c
# a.out
Input argument for asinh: -100
asinh(-100.000000)=-5.298342
# ldd a.out
        libc.so.6 => /lib/libc.so.6 (0x40007000)
	/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x2aaaa000)
# ls -l /lib/libc.so.6
lrwxrwxrwx   1 root     root           26 Dec 11 08:16 /lib/libc.so.6 -> glibc-2.0-981211/libc.so.6

I am running glibc 2.0.7 981211.


-- 
H.J. Lu (hjl@gnu.org)