On 4/22/08, tribur at vision.ee.ethz.ch <tribur at vision.ee.ethz.ch> wrote: > Dear Matt, > > > This does not make sense to me. You decide how PETSc partitions things (if > > you want), And, I really do not understand what you want in parallel. > > If you mean > > that you solve the local Schur complements independently, then use a local > > matrix for each one. The important thing is to work out the linear algebra > prior > > to coding. Then wrapping it with PETSc Mat/Vec is easy. > > > > The linear algebra is completely clear. Again: I have the local Schur > systems given (and NOT the solution of the local Schur systems), and I would > like to solve the global Schur complement system in parallel. The global > Schur complement system is theoretically constructed by putting and adding > elements of the local systems in certain locations of a global matrix. > Wrapping this with PETSc Mat/Vec, without the time-intensive assembling, is > not easy for me as a PETSc-beginner. But I'm curious of the solution you > propose...
Did you verify that the Schur complement matrix was properly preallocated before assembly? This is the likely source of time. You can run with -info and search for "malloc" in the output. Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
