How to initialize a PETScMatrix with given sizes?

Question

Dear all,
I would like to initialize a PETScMatrix A with given sizes mxm. In FeniCS 1.0.0, it is very simple, I can call A.resize(m,m). However, this method was removed in the new version, FeniCS 1.2.0. Temporarily, I have to use assemble method to initialize a matrix but it is not a good way for my problem. Could you please show me how to initialize such the matrix?
Thank you very much for your help,
Best regards,
Dang

Answer 1

You need to construct a TensorLayout object, and use this to initialise the PETScMatrix.

The old interface was unfortunate. It is not suitable for sparse matrices, which is why it has been removed.