Bug 3308
| Summary: | floor() function in libm (glibc-2.1) is broken on Alpha. | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | niles |
| Component: | glibc | Assignee: | Cristian Gafton <gafton> |
| Status: | CLOSED WORKSFORME | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | 6.0 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | alpha | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 1999-07-09 22:17:43 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
Try this C program:
#include <stdio.h>
#include <math.h>
int
main()
{
printf("%f\n",floor(0.1));
return 0;
}
It returns with 36028797018963968.000000
This would explain 100% of the funny results I was seeing.
This would also explain why using the CMPL fixed the problem,
it had it's own implementation of the floor() function.
That program works for me; I can not reproduce the problems reported. What are the compiler flags used to compile the test code? This same problems shows up on my machine. I am running RedHat 6.1 on an AlphaStation 4/200 (233Mhz EV4 21064). This bug occurred in both the 6.0 and 6.1 releases. This bug shows up for an upgrade and a clean install. Please move this bug back to the active list. I can't go and rework all of the makefiles for all of the applications which depend on the broken glibc to use cpml instead. |
I wish I could be more specific, but then I would be able to fix it. Here's the simplest FORTRAN program that demos the problem: WRITE(*,*) DNINT(0.0D0) END Reports 3.6028797E+16 instead of 0. Now, you may jump to the conclusion that this is just a DNINT() function problem, but in general, there's some very funky math problems on the Alpha that all quickly go away (100%) if one compiles with "-lcpml" the Compaq portable math library (including the above example). Hence, my guess it has something to do with the GNU clib-2.1 libm.