[petsc-users] unsure about ex19 test results

[Dominik Szczerba]

I am on a Cray system, where I have configured and built petsc 3.2 p5
myself, only using the vendor provided mpi, all the other packages
(parmetis, hypre, mumps) are built with --download-package. "Make ...
test" does not work here to verify the correct build because users do
not have access to mpiexec. So I do the test by hand, and I am unsure
about what I am getting. When executing the test ex19 with the
system's scheduler I get this output:

lid velocity = 0.0204082, prandtl # = 1, grashof # = 1
Number of Newton iterations = 2
lid velocity = 0.0204082, prandtl # = 1, grashof # = 1
Number of Newton iterations = 2

It's quite different from the expected output in ex19_1.testout:

lid velocity = 0.0016, prandtl # = 1, grashof # = 1
Number of Newton iterations = 2
lid velocity = 0.0016, prandtl # = 1, grashof # = 1
Number of Newton iterations = 2

Does it mean that I have screwed up the build somehow, or is this
somehow the effect of the batching system, or just numerical
uncertainty due to the parallel computation? Note: I get the same
result with 1 and a few MPI processes.

Many thanks for any ideas.

Dominik