[SciPy-dev] sparsetools - new and (hopefully) improved!

Robert Cimrman cimrman3 at ntc.zcu.cz
Fri Jan 5 04:44:10 CST 2007


Nathan Bell wrote:
> On 1/4/07, Robert Cimrman <cimrman3 at ntc.zcu.cz> wrote:
>> Hi Nathan, I have not had time to look at your code yet (just returned
>> from holidays) but the description looks great!
>>
>> One umfpack-related note - the solver requires the CSC/CSR column/row
>> indices sorted in ascending order. Does your implementation contain a
>> function to ensure_sorted_indices()?
> 
> Not currently, but it would be trivial to add.  Converting from
> CSR<->CSC (a linear time operation) has the side effect of sorting the
> column/row indices.  Two conversions (CSR->CSC->CSR) would produce the
> desired result in the original format.
> 
> I will add ensure_sorted_indices() to csr_matrix and csc_matrix.

Good! Going CSR->CSC->CSR would be too inefficient, IMHO. Maybe we could 
add a flag to the CSR/CSC matrix class saying that it has sorted indices 
to make the check trivial. It should be added as keyword argument to the 
matrix constructor, too.

r.



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