Direct solve preconditioner for Trilinos Block Sparse

[Aiden Huffman]

I can't seem to find a way to use the BlockwiseDirect preconditioner on TrilinosWrappers::BlockSparseMatrix objects? The signature for BlockwiseDirect only takes the base SparseMatrix object.

Would it be possible to temporarily forget the block structure and recover the underlying SparseMatrix to construct the preconditioner?

Cheers,

Aiden

[Wolfgang Bangerth]

There is no underlying SparseMatrix for block matrices. Each block
stores its own SparseMatrix object. They know nothing of each other.

But you can of course create a preconditioner that applies a
BlockwiseDirect method to each of the diagonal blocks of your block
matrix, assuming that each of these blocks is invertible.

Best
W.