On Tue, Feb 16, 2016 at 12:00 PM, John Peterson <jwpeter...@gmail.com> wrote:
> On Tue, Feb 16, 2016 at 9:51 AM, Harshad Sahasrabudhe <hsaha...@purdue.edu > > > wrote: > > > Hi, > > > > I'm using QTrap to integrate a differential equation for a generalized > > eigenvalue problem. I'm using CondensedEigenSystem to solve the equation. > > When I use QTrap, I get a diagonal B matrix in > > > > A \psi = \lambda B \psi > > > > So my question is: Is the sparsity pattern of B set according to the > > quadrature rule or is it the same as A? > > > A and B share the same sparsity pattern, which is determined by the element > connectivity and FE types involved, but not quadrature rules. > One interesting thing that I didn't realize for a long time is that PETSc condenses the sparsity pattern when you call matrix->close(), i.e.: http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatAssemblyBegin.html "Space for preallocated nonzeros that is not filled by a call to MatSetValues() or a related routine are compressed out by assembly. If you intend to use that extra space on a subsequent assembly, be sure to insert explicit zeros before MAT_FINAL_ASSEMBLY so the space is not compressed out." So in this case, if you're using PETSc/SLEPc, then B will be diagonal after the matrix is "closed". David ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
