[SciPy-dev] f2py and ATLAS crashing bug

Charles R Harris charlesr.harris at gmail.com
Sun Nov 8 20:14:56 EST 2009


On Sun, Nov 8, 2009 at 4:42 PM, Anne Archibald
<aarchiba at 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>

Chuck
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