[SciPy-dev] f2py and ATLAS crashing bug

Charles R Harris charlesr.harris@gmail....
Sun Nov 8 19:26:24 CST 2009


On Sun, Nov 8, 2009 at 6:14 PM, Charles R Harris
<charlesr.harris@gmail.com>wrote:

>
>
> On Sun, Nov 8, 2009 at 4:42 PM, Anne Archibald <aarchiba@physics.mcgill.ca
> > wrote:
>
>> Hi,
>>
>> I am still trying to fix the bug where non-aligned matrices can cause
>> ATLAS to segfault, and I think I need to improve my understanding of
>> f2py somewhat.
>>
>> First of all, I'll note that the bug appears in several routines (eig,
>> svd, qr, rq, hessenberg, and schur that I have found so far) but only
>> when the overwrite_a flag is passed in. So I tried to determine how
>> overwrite_a is used in these routines, and I am puzzled. The python
>> routines appear to pass it unmodified to the FORTRAN routines. The
>> .pyf files mention it in the python call signatures, but nowhere else;
>> from the f2py files it looks like it should be ignored. But clearly it
>> has some effect, since it allows crashes.
>>
>>
> I'm going to guess there is a conflict between the overwrite flag and the
> copy flag. Might be considered a bug, but I'm not sure how those two should
> interact anyway. The quick fix would seem to be to not use overwrite, which
> might have the same effect you are shooting for with the copy flag. Pearu
> probably needs to take a look at the flag interaction and maybe we can maybe
> fix things differently at some point. Does everything work if you just don't
> set the overwrite flag?
>
> <snip>
>
>
A question, are these problems specific to the pentium machine, and if so,
where did the ATLAS come from. I had some problem with segfaults on a
pentium back when and had to build my own ATLAS to get around them.

Chuck
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