[petsc-users] DMComposite and Matrix construction

Gideon Simpson gideon.simpson at gmail.com
Wed Jul 29 11:51:15 CDT 2015

That’s generating malloc errors:

[0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
[0]PETSC ERROR: Argument out of range
[0]PETSC ERROR: New nonzero at (10,0) caused a malloc
Use MatSetOption(A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE) to turn off this check

I suspect this is because DMCreateMatrix is picking a sparsity pattern which is not consistent with what I need.


> On Jul 28, 2015, at 10:10 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>  DMCreateMatrix() ? 
>> On Jul 28, 2015, at 9:02 PM, Gideon Simpson <gideon.simpson at gmail.com> wrote:
>> I’m working with a DMComposite where I have a DMRedundant with 2 parameters, and then a standard DMDACreate with some number of entires that I would like to have distributed.  For concreteness, suppose it is 
>> DMCompositeCreate(PETSC_COMM_WORLD, &packer);
>> DMRedundantCreate(PETSC_COMM_WORLD, 0, 2, &p_dm);
>> DMCompositeAddDM(packer,p_dm);
>> DMCompositeAddDM(packer,u_dm);
>> DMCreateGlobalVector(packer,&U);
>> Now, I would like to construct a matrix for this problem that can be used for computing Jacobians in a nonlinear solve.  Is there a way to get the matrix size to layout in a “useful” way, in the sense that the first process, which owns the two degrees of freedom of p_dm and the first N0 number of the rows of u_dm, controls the corresponding N0+2 rows of the matrix, and analgously for the second process has the next N1 rows of the u_dm vector, and has the next N1 rows of the matrix?
>> -gideon

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