[petsc-users] Operator matrix as a Matrix-free matrix

[Umut Tabak]

Dear all,

I would like to create an operator matrix like

(I - 0.5 C^{-1}(C+kD))

for linear iterative solvers, where k is a given scalar and C and D are 
matrices from a FE  discretization.

Moreover, the second part of the operator matrix can be constructed 
efficiently by using a matrix-vector product and a forward-backward 
substitution since I have the factorization of C which is a symmetric 
matrix.

I guess I should use matrix free operations and create the two matrices 
as shell matrices such as M1 (for I) and M2 (for the rest of above) and 
sum them, is this the most efficient way to do this?

Best wishes,
Umut

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