[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Bug#448527: marked as done (libc6: hypotf underflows for small inputs)

Your message dated Fri, 16 Nov 2007 15:19:18 +0100
with message-id <20071116141916.GA24902@volta.aurel32.net>
and subject line libc6: hypotf underflows for small inputs
has caused the attached Bug report to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what I am
talking about this indicates a serious mail system misconfiguration
somewhere.  Please contact me immediately.)

Debian bug tracking system administrator
(administrator, Debian Bugs database)
--- Begin Message --- 
Package: libc6
Version: 2.3.6.ds1-13
Severity: normal

The hypotf function in libm produces incorrect results for the code
below.

Comparing Debian 4 glibc source with current upstream source code shows
a change in the constants used for bit fiddling in the function. It
should be possible to backport the fix.

Current implementation on Debian 4 produces a result of 0 instead of
2.009718e-14.

#include <math.h>
#include <stdio.h>

int main() {
   float a,b,c;

   a = -1.81341284e-16;
   b = 2.00963666e-14;

   c = hypotf(a,b);
   
   printf("result of hypotf(%e,%e) is %e.\n", a, b, c); }

-- System Information:
Debian Release: 4.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-4-amd64
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)

Versions of packages libc6 depends on:
ii  tzdata                        2007b-1    Time Zone and Daylight
Saving Time

libc6 recommends no packages.

-- no debconf information

--- End Message ---
--- Begin Message --- 
Version: 2.6-1

On Mon, Oct 29, 2007 at 03:46:31PM -0400, Duncan Po wrote:
> Package: libc6
> Version: 2.3.6.ds1-13
> Severity: normal
> 
> The hypotf function in libm produces incorrect results for the code
> below.
> 
> Comparing Debian 4 glibc source with current upstream source code shows
> a change in the constants used for bit fiddling in the function. It
> should be possible to backport the fix.
> 
> Current implementation on Debian 4 produces a result of 0 instead of
> 2.009718e-14.
> 
> #include <math.h>
> #include <stdio.h>
> 
> int main() {
>    float a,b,c;
> 
>    a = -1.81341284e-16;
>    b = 2.00963666e-14;
> 
>    c = hypotf(a,b);
>    
>    printf("result of hypotf(%e,%e) is %e.\n", a, b, c); }
> 

Marking this bug as fixed in glibc 2.6-1.


-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net

--- End Message ---
Reply to: