[petsc-users] elimination of trivial entries in a matrix

[Dominik Szczerba]

My matrix has many trivial entries (A_{ii}=1, A_{i!=j}=0, b_i = b0)
that I want to eliminate to reduce the solving time, re-inserting them
at the end into the solution vector.
Of course I can do it all by creating a second matrix and doing
related book-keeping on my own, but was wondering if there is some
functionality in Petsc to facilitate it.
If so, I would be grateful for just a list of relevant functions to look at.

Many thanks
Dominik