[petsc-users] Question on non-zero pattern

[Sanjay Govindjee]

When I pre-allocated, I preallocated sufficient on and off and off 
processor memory for
all possible non-zero patterns.  So I assume that there will not be any 
mallocs necessary.
Or am I mis-understanding how the preallocation works?

-sanjay



On 3/14/13 12:52 PM, Satish Balay wrote:
> But you might have mallocs with the new nonzero structure. Its proably
> more efficient to destroy/create a new mat with the new structure.
>
> Satish
>
> On Thu, 14 Mar 2013, Sanjay Govindjee wrote:
>
>> Found my answer, use
>>
>>            call MatSetOption(Kmat,MAT_NEW_NONZERO_LOCATIONS,PETSC_TRUE,ierr)
>>
>> after the MatAssemblyEnd( ).
>>
>>
>> On 3/14/13 11:28 AM, Sanjay Govindjee wrote:
>>> Is there a mechanism for resetting a matrix's non-zero pattern?
>>>
>>> In particular,  I have a preallocated a matrix, set the values, and
>>> assembled it.
>>> And used it to solve a problem.
>>>
>>> Now I would like to zero it, and reassemble it with a different non-zero
>>> pattern.
>>> Note the matrix has been preallocated so that it can accommodate both
>>> non-zero
>>> patterns.
>>>
>>> -sanjay
>>