http://www.mcs.anl.gov/petsc/documentation/faq.html#schurcomplement
On Nov 18, 2011, at 7:02 AM, Thomas Witkowski wrote: > In my current FETI-DP implementation, the solution of the Schur complement on > the primal variables is done by an iterative solver. This works quite good, > but for small and mid size 2D problems I would like to test it with direct > assembling and inverting the Schur complement matrix. In my notation, the > matrix is defined by > > S_PiPi = K_PiPi - K_PiB inv(K_BB) K_BPi > > "Pi" are the primal and "B" the non-primal variables. K_BB is factorized with > a (local) direct solver (umpfack or mumps). But how can I create a matrix > from the last expression? Is there a way to do a matrix-matrix multiplication > in PETSc, where the first matrix is the (implicit defined) dense inverse of a > sparse matrix, and the second matrix is a sparse matrix? Or is it required to > extract the rows of K_BPi in some way and to perform than a matrix-vector > multiplication with inv(K_BB)? > > Thomas
