Avoiding assembly with MatDiagonalSet call for zeroed matrix to preserve preallocated space

[BAYRAKTAR Harun]

Hello,

 

I have a rather simple question. For a Matrix that was preallocated with
the correct diagonal and offdiagonal nonzero counts the following
operations cause a deallocation of all data except the diagonal which
casues later MatSetValues to have to reallocate.

 

MatCreateSeqAIJ

MatZeroEntries

MatDiagaonalSet

 

Using -info and the debugger I see that MatDiagonalSet ends up calling
MatDiagonalSet_Default which forces an assembly. Is there a way to do
the same thing and preserve the preallocated storage for future use by
MatSetValues? I tried MatSetOption with MAT_KEEP_ZEROED_ROWS and
MAT_IGNORE_ZERO_ENTRIED but it did not help.

 

Thanks a lot,

Harun

 

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