[SciPy-user] multiplying sparse matrices in scipy-0.4.8?

Ed Schofield schofield at ftw.at
Tue Mar 28 17:48:51 CST 2006


On 29/03/2006, at 1:13 AM, Travis Oliphant wrote:

> Ed Schofield wrote:
>>
>>
>> Yes, this is a bug.
>>
>> Travis, could you please take a look at this?  The FORTRAN  
>> functions dcscmucsc and dcscmucsr both seem to be returning  
>> incorrect values in indptr.  In fact, could you please explain the  
>> Python code in matmat() that calls these functions?  I'd like to  
>> understand what the "while 1" loop is for, and in particular why  
>> we have
>>     c, rowc, ptrc, irow, kcol, ierr = func(*args)
>> when c, rowc, etc are part of *args anyway.
>
> The arguments are input and output arguments because that is my  
> understanding of f2py's preference if something is both input and  
> ouput rather than using an in-place argument.

To minimize side-effects?  Okay ;)

> The while True:  loop is so that resizing can occur if the guess on  
> how many non-zero elements to reserve for the output matrix is wrong.
> There were some problems with the re-entry that I've now fixed.   
> The tests you added to SciPy now pass.

Thanks, Travis!

-- Ed



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