On Sun, Nov 20, 2011 at 09:57:13PM +0000, Garth N. Wells wrote: > On 20 November 2011 21:02, Anders Logg <l...@simula.no> wrote: > > On Sun, Nov 20, 2011 at 08:40:02PM +0000, Garth N. Wells wrote: > >> On 20 November 2011 20:32, Anders Logg <l...@simula.no> wrote: > >> > The unit test currently failing on the Mac buildbot (timing out) is > >> > failing on my machine (Ubuntu 11.10) with a PETSc error claiming that > >> > the vector in question is not ghosted. > >> > > >> > I've tracked it down to the plotting from the C++ eigenvalue demo, and > >> > the call to gather() from within interpolate_vertex_values. > >> > > >> > The problem is that the Function to be plotted is created from a > >> > solution vector x from the eigenvalue problem like so: > >> > > >> > Function u(V, x); > >> > > >> > Since x does not come from a Function to begin with, it was not > >> > initialized with ghost values, so then later when > >> > u.interpolated_vertex_values is called, the call to gather() fails. > >> > > >> > Should there be a test for whether ghost values exist in either > >> > PETScVector or Function (_have_ghost_values)? > >> > > >> > >> Take a look here on how to test: > >> > >> http://lists.mcs.anl.gov/pipermail/petsc-dev/2011-November/006286.html > > > > ok, so VecIsGhosted is in petsc-dev. > > If you follow the thread, there is a solution for PETSc 3.2.
Yes I noticed. We could copy-paste that if we need it now. > > It would be good to use that in > > the future but then we need the same for Epetra. > > > > Epetra doesn't support ghosting - it's been added to our wrappers, so > it's easy to detect. ok. > > But it still doesn't solve the problem with the constructor > > > > Function u(V, x); > > > > Does it make sense in parallel when x may not have the correct > > ghosted values so calls to interpolate_vertex_values (and likely other > > functions) may fail? > > > > It will be problematic when getting values from u, e.g. when used as a > coefficient. A better approach is > > Function u(V); > *u.vector() = x; // Not sure the syntax is right Should there be a test in that constructor that the input vector has the correct layout, in particular that it has all dofs it needs? -- Anders > Garth > > > > > > >> Garth > >> > >> > On top of this, the call to plot() does not work in parallel from C++ > >> > anyway so it's easy to make the bug disappear (by moving the check in > >> > the plot function earlier to before the call to > >> > interpolate_vertex_values), but it exposes a problem with the > >> > constructor > >> > > >> > Function u(V, x); > >> > > >> > which may not make sense if x does not have the proper layout. > >> > > >> > > >> > _______________________________________________ > >> > Mailing list: https://launchpad.net/~dolfin > >> > Post to : dolfin@lists.launchpad.net > >> > Unsubscribe : https://launchpad.net/~dolfin > >> > More help : https://help.launchpad.net/ListHelp > >> > > >> > >> > >> > > _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : dolfin@lists.launchpad.net Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
