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

[Xin Zhao]

Dear all,

I generate a matrix L by
DA =PETSc.DA().create(...some...)
L = DA.create()
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
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