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

Nils Wagner nwagner@iam.uni-stuttgart...
Thu Mar 8 12:17:32 CST 2007


On Thu, 08 Mar 2007 18:10:30 +0100
  Robert Cimrman <cimrman3@ntc.zcu.cz> wrote:
> Robert Cimrman wrote:
>> Nils Wagner wrote:
>>> Just out of interest
>>>
>>> Is there something comparable with
>>>
>>> sigma_solve = linsolve.splu(A - sigma*B).solve
>>>
>>> available in UMFPACK ?
>> 
>> Sure, although it is not a oneliner. This is the 
>>relevant part of the
>> docstring:
> 
>> Would you be interested in exposing this in linsolve, 
>>as, say,
>> 
>> def factorized( A ):
>>     if isUmfpack and useUmfpack:
>> 	# This must be written...
>>     else:
>>         return splu( A ).solve
> 
> 
> 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.
> 
> cheers,
> r.
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Great ! Thank you very much !

Nils


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