Hi Jed, thanks for replying. In fact, the problem I sent the results from is a dynamic problem of a simply supported beam subjected to a constant load at the center, so I'm integrating in time. The material is linear elastic so the stiffness matrix doesn't change in non-zero structure. Of course the right hand side changes, but I don't think this is the problem because at some point it takes it goes back to just a few iterations to solve. The behavior is cyclic, but I don't understand the reason for this. I've noticed the same behavior of the solver also in quasi-static problems (increasing the load gradually but not integrating over time).
Alejandro M. Arag?n On Apr 26, 2011, at 9:52 AM, Jed Brown wrote: > 2011/4/26 Alejandro Marcos Arag?n <alejandro.aragon at gmail.com> > As you can see, the second iteration takes more than 40 seconds to solve. > Could some explain why this is happening and why he number of iterations is > increasing dramatically between solves? > > What has changed between solves? If this is part of a nonlinear problem, it > might have just gotten harder to solve. If the linear system is the same, the > right hand side for the first problem was probably degenerate (roughly > speaking, having significant energy in only a few Krylov modes). -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110426/c602f3b0/attachment.htm>
