dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

On 20 November 2011 20:32, Anders Logg <logg@xxxxxxxxx> 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

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.
>
> --
> Anders
>
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-- 
Garth N. Wells
Department of Engineering, University of Cambridge
http://www.eng.cam.ac.uk/~gnw20