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. > 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. > 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 Garth > -- > Anders > > >> 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
