Dear all,
I am developing a F90 application using several other libraries (such as FFTW) and aimed at being interfaced with a Python software via f2py.
In terms of compilation, no worries : everything goes just fine. However, when using it, the whole software returns regularly NaNs instead of the values it’s supposed to calculate.
I tried to call the routines I developed from a F90 standard program and everything works just fine. I therefore assume that the problem comes from the Python interface.
I read on this forum some related messages proposing a change in dlopen behaviour ; it actually worked, but when increasing the size of my variables, it started again to yield NaN.
Now, my question is : has someone ever met such a puzzling issue? And if so what did you do to correct it? I would be really glad to get some input.
FYI I use the PGF90 v8.0 on a Linux RedHat 5 box and a Python 2.2 interpreter.
Thanks to all for reading.
Hi everyone,
any input? This issue is really puzzling… and quite a pain!
I can post more details about the programs if needed. It’s just I don’t know how relevant this would be regarding the problem we encounter with this software.
Ok, I’ve got f2py installed on my system and am able to run some basic tests. It looks to me that it’s simply a wrapper that allow you to hook your Fortran application into a python interface.
Personally, I first make sure your application works outside of Python. If you can recreate the behavior in native Fortran it should be a lot easier to debug.
If your application works outside of f2py, then I would contact the f2py mailing list ( http://cens.ioc.ee/projects/f2py2e/#mailing-list) since it would then more likely be a problem with f2py then the Fortran code.
Hi Mat,
First off, thank you very much for your help. I indeed tried to use the application outside of Python. And it actually worked pretty well. Therefore, as you propose, I will give a try to the f2py mailing list.
In any ways, I will post the answers I get if any.
Best regards,
Pierre-François
Hi Mat, hi all,
Well I finally found out the issue wasn’t coming from f2py at all (although the software’s behaviour is quite different from one time to another when wrapping with f2py).
After a thorough (though unfinished) debugging process, I found that FFTW libraries might cause my “NaN” issue. I however still need to further investigate this. If anyone has some experience with interfacing FFTW libs with F90, I am looking for an input here (again).
Regards
Pierre-François