Nabble - math-atlas-errors

ATLAS s/cGEMM error

2009-08-13T16:08:08Z

Guys,

If ATLAS chooses an NB > 84, then it is possible for SGEMM and CGEMM to
produce the wrong answer for M that are multiples of 14. If you use
the architectural defaults on a 64-bit AMD K10h, then you definitely
have this error, and if you don't use arch defs on other x86 platforms
you could potentially have it (if the search chooses NB > 84 and uses
this cleanup routine).

For details and the fix, see:
http://math-atlas.sourceforge.net/errata.html#mu14nb120

Regards,
Clint

**************************************************************************
** R. Clint Whaley, PhD ** Assist Prof, UTSA ** www.cs.utsa.edu/~whaley **
**************************************************************************

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bug in ATLAS c/zGEMM

2009-07-08T14:57:54Z

Guys,

There's a bug in complex GEMM that can cause an unitialized memory
read when c/z GEMM is called with large K and small M and N. The fix is
described at:
http://math-atlas.sourceforge.net/errata.html#JITB02

Cheers,
Clint

**************************************************************************
** R. Clint Whaley, PhD ** Assist Prof, UTSA ** www.cs.utsa.edu/~whaley **
**************************************************************************

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ATLAS performance bug for all architectures

2008-06-06T13:12:26Z

There is a performance bug that causes a fairly large performance drop on
all architectures. This bug is present in both ATLAS 3.8.0 and 3.8.1.
The explanation and fix is available at:
http://math-atlas.sourceforge.net/errata.html#JITcpBug

Regards,
Clint

**************************************************************************
** R. Clint Whaley, PhD ** Assist Prof, UTSA ** www.cs.utsa.edu/~whaley **
**************************************************************************

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Illegal reading of C in ATLAS complex GEMM

2008-05-23T13:07:57Z

An error has been found where ATLAS3.8.1 will occasionally read C even when
BETA={0.0,0.0} in complex GEMM. Details, including the fix are available at
http://math-atlas.sourceforge.net/errata.html#JITNaN

Regards,
Clint

**************************************************************************
** R. Clint Whaley, PhD ** Assist Prof, UTSA ** www.cs.utsa.edu/~whaley **
**************************************************************************

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two known errors in ATLAS 3.8.0

2008-01-14T14:29:18Z

I thought I had already sent a message about this, but the error archive
doesn't show it.

There have been two errors found in 3.8.0, and errata fixing them have
been issued. The most important error is:
http://math-atlas.sourceforge.net/errata.html#RMAAT
This causes GEMM to compute the wrong answer for row-major C = alpha*A*A' or
C = alpha*A'*A.

The second error only effects configure on the Pentium-M, which is
misidentified as a CoreDuo. The errata and fix are at:
http://math-atlas.sourceforge.net/errata.html#PM-CD

Regards,
Clint

**************************************************************************
** R. Clint Whaley, PhD ** Assist Prof, UTSA ** www.cs.utsa.edu/~whaley **
**************************************************************************

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Error in complex GEMM for C = A*A'

2006-11-20T16:36:26Z

Guys,

A user just discovered an error that effects all ATLAS releases at least
as far back as 3.3. Essentially, complex GEMM (ZGEMM & DGEMM) can produce
the wrong answer for the special case where B = transpose(A). Here's
the errata entry describing the fix:
http://math-atlas.sourceforge.net/errata.html#AAT

Best regards,
Clint

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