On 11/01/2011 03:41 PM, Roy Stogner wrote: > > On Tue, 1 Nov 2011, David Knezevic wrote: > >> On 11/01/2011 03:28 PM, Roy Stogner wrote: > >>> The problem seems to be some issue with the default iterative solvers >>> we tell SLEPc to use; it looks like for some reason they're getting a >>> "norm" of their initial random starting vector that isn't a >>> non-negative real number. I'm not sure how this would happen, though >>> a Google search suggests that we're not the first people to run into >>> this IPNorm error when doing a generalized eigenproblem. >> >> Interesting. So it's not a bug per se, good to know. > > It might still point to a bug. Our matrices in ex17 should both be > real-valued symmetric, right? The stiffness matrix is not invertible, > but I don't see how that would cause a problem in C but not in R.
True. One thought is that I've always thought that ex17 was a bit strange since we're looking for sup_v a(v,v) / m(v,v) which is unbounded as h --> 0. Perhaps things are more fragile because of this high-frequency mode? Does ex17 work with complex numbers if you uncomment the line: eigen_system.eigen_solver->set_position_of_spectrum(SMALLEST_MAGNITUDE); ------------------------------------------------------------------------------ RSA® Conference 2012 Save $700 by Nov 18 Register now! http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
