[petsc-users] petsc4py and numpy

[Lisandro Dalcin]

On 8 May 2012 12:04, Matthew Knepley <knepley at gmail.com> wrote:
> On Tue, May 8, 2012 at 11:00 AM, Christian Staudt
> <christian.staudt at ira.uka.de> wrote:
>>
>> Matthew Knepley <knepley at gmail.com> wrote:
>>
>> a) Is there an easy and efficient way to convert a numpy.ndarray to a
>>
>> PETSc.Vec or PETSc.Mat (and vice-versa)?  (A PETSc.Vec.getArray() returns
>> a
>>
>> numpy.ndarray, though I have found no such method for PETSc.Mat yet. )
>>
>>
>>
>> If you are using dense matrices (MATDENSE) then MatGetArray() works.
>>
>>
>> I don't think this is implemented in petsc4py: At least, there's no method
>> PETSc.Mat.getArray()
>
>
> If you ask Lisandro for it, he will put it in.
>

Matt, I've never put that in just because I'm not sure how to make it
general. PETSc have many different matrix formats, and MatGetArray()
call is like a hack, where you can get very different things (the "1D"
values of an AIJ matrix, the "2D" values of a dense matrix in Fortran
order). What about MPIAIJ, what should I return to users? Can you
suggest some approach or API to implement this (I mean, how to get
arrays for the various matrix types)?

-- 
Lisandro Dalcin
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