[petsc-users] Problem with Mat.setpreallocationNNZ in petsc4py

[Xin Zhao]

So if it is written as
if PETSc.COMM_WORLD.get_Rank() == 0:
L.setPreallocationNNZ((3,2))

will it achieve what I intend to do?



On Sat, Jul 7, 2012 at 6:04 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Sat, Jul 7, 2012 at 11:02 AM, Xin Zhao <sean.null at gmail.com> wrote:
>
>> yeap...sorry...
>> L=DA.createMat()
>>
>> then
>> L.setPreallocationNNZ((3,2))
>>
>
> As I said, its already preallocated.
>
>   Matt
>
>
>> On Sat, Jul 7, 2012 at 6:01 PM, Matthew Knepley <knepley at gmail.com>wrote:
>>
>>> On Sat, Jul 7, 2012 at 10:58 AM, Xin Zhao <sean.null at gmail.com> wrote:
>>>
>>>> Dear all,
>>>>
>>>> I generate a matrix L by
>>>> DA =PETSc.DA().create(...some...)
>>>> L = DA.create()
>>>>
>>>
>>> Is this createMatrix()? The matrix returned from a DA is already
>>> preallocated.
>>>
>>>    Matt
>>>
>>>
>>>> Then I want to preallocate memory for L
>>>> L.setPreallocationNNZ((3,2))
>>>> This works when for mpiexec -np 1
>>>> but it gives the error message below when mpiexec -np 4
>>>>
>>>> [3] MatAnyAIJSetPreallocation() line 311 in
>>>> petsc4py-1.2/src/include/custom.h
>>>> [3] Operation done in wrong order
>>>> [3] matrix is already preallocated
>>>>
>>>> How to solve this?
>>>>
>>>> Thanks in advance.
>>>>
>>>> Cheers,
>>>> Xin
>>>>
>>>
>>>
>>>
>>> --
>>> What most experimenters take for granted before they begin their
>>> experiments is infinitely more interesting than any results to which their
>>> experiments lead.
>>> -- Norbert Wiener
>>>
>>
>>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
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