[SciPy-user] eigenvalues of sparse matrix

David Grant david at dwavesys.com
Thu Oct 28 12:22:19 CDT 2004

Travis Oliphant wrote:

>> Does anyone know how much work it would be to get ARPACK support in 
>> scipy?  Even just minimal support.  This is totally new ground for 
>> me, so I'd like to know if I'm biting off more than I can chew.
> Not a lot for simple support if you use f2py.
> My suggestion would be to write an f2py interface for the desired 
> routines and we can build up from there.
I assume your suggestion does not involve using this at all: 
http://jrfonseca.dyndns.org/work/phd/ ?
I believe Josa Fonseca was going to use f2py, but he didn't.

Here is from his web page:

"These bindings weren't generated with any automatic binding generation 
tool. Even though I initially tried both PyFortran and f2py, both showed 
to be inappropriate to handle the specificity of the ARPACK API. ARPACK 
uses a /reverse communication interface/ where basically the API 
sucessively returns to caller which must take some update steps, and 
re-call the API with most arguments untouched. The intelligent (and 
silent) argument conversions made by the above tools made very difficult 
to implement and debug the most simple example. Also, for large-scale 
problems we wouldn't want any kind of array conversion/transposing 
happening behind the scenes as that would completely kill performance."

"Therefore the bindings are faithfull to the original FORTRAN API and 
are not very friendly as is. Nevertheless a Python wrapper to these 
calls can easily be made, where all kind of type conversions and 
dummy-safe actions can be made."

So who is right?


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