[Numpy-discussion] Re: [SciPy-user] multiplying sparse matrices in scipy-0.4.8?

Travis Oliphant oliphant.travis at ieee.org
Tue Mar 28 15:14:00 CST 2006

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.

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.


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