I added ", which is often the null space of the operator without boundary conditions" to the web page doc for MatSetNearNullSpace.
On Wed, Feb 24, 2016 at 10:57 AM, Matthew Knepley <[email protected]> wrote: > On Wed, Feb 24, 2016 at 9:45 AM, Manav Bhatia <[email protected]> > wrote: > >> Hi, >> >> I typically apply Dirichlet BCs by modifying the Jacobin and rhs: >> zero constrained rows of matrix with 1.0 at diagonal, and zero >> corresponding rows of rhs. >> >> While using GAMG, is it still recommended to provide the near-null >> space (given that the zero-eigenvalues have been removed by specification >> of DIrichlet BCs)? >> > > Yes. > > >> If that information is still needed, should the vectors be modified >> in any manner to be consistent with the Dirichlet BCs? >> > > No. You can see that if you take a small piece of the domain, apart from > the boundary, it will have this as a null space. > > Matt > > >> Thanks, >> Manav >> >> >> > > > -- > 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 >
