Dear Developers,

I am solving an evolution problem, which works nicely, but I am trying to optimize it. As not every part of my system matrix changes in each step, I would like to make my code more efficient by assembling a system from block matrices, evaluating only the terms which are necessary to be updated in each step. I am attempting this using the PETSc interface. Therefore, it would be more efficient to do as much of this as I can using PETSc numbering. To be able to do this, I need the PETSc functions MatDiagonalSet, MatAXPY and MatAYPX. I kindly ask you to consider making these functions available in FreeFem.