[SciPy-user] linsolve.factorized was: Re: Using umfpack to calculate a incomplete LU factorisation (ILU)

Neilen Marais nmarais@sun.ac...
Thu Mar 22 09:34:12 CDT 2007

Hi Robert!

On Thu, 08 Mar 2007 18:10:30 +0100, Robert Cimrman wrote:

> Robert Cimrman wrote:
> Well, I did it since I am going to need this, too :-)
> In [3]:scipy.linsolve.factorized?
> ...
> Definition:     scipy.linsolve.factorized(A)
> Docstring:
>     Return a fuction for solving a linear system, with A pre-factorized.
>     Example:
>       solve = factorized( A ) # Makes LU decomposition.
>       x1 = solve( rhs1 ) # Uses the LU factors.
>       x2 = solve( rhs2 ) # Uses again the LU factors.
> This uses UMFPACK if available.

This is a useful improvement, thanks. But why not just extend
linsolve.splu to use umfpack so we can present a consistent interface? The
essential difference between factorized and splu is that you get to
explicity control the storage of the LU factorisation and get some
additional info (i.e. the number of nonzeros), whereas factorised only
gives you a solve function. The actual library used to do the sparse LU is
just an implementation detail that should abstracted wherever possible, no?

If nobody complains about the idea I'm willing to implement it.


> cheers,
> r.

you know its kind of tragic 
we live in the new world
but we've lost the magic
-- Battery 9 (www.battery9.co.za)

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