I am learning PETSc following the tutorials of the distribution (version 3.4.1). My question is about the KSPView(ksp,PETSC_VIEWER_STDOUT_WORLD); (line 216) of ex7.c (KSP tutorial). It teaches how to use PCBJACOBI, setting different solvers for each PC block. When I use

mpirun -n 4 ./ex7 -m 20 -ksp_type cg

the output is kind of a mess, like if there wasn't order on the output (and difficult to understand). I just figured out this when I did the serial test

mpirun -n 1 ./ex7 -m 20 -ksp_type cg

Someone can tell me what is going on, since when using PETSC_VIEWER_STDOUT_WORLD the process [0] should print the outputs of the others processes in some (random) order, but without mixing the outputs?


closed as off-topic by Daniel Shapero, Christian Clason, GertVdE, Godric Seer, Thomas Klimpel Aug 11 '13 at 21:15

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  • $\begingroup$ Hi Adriano, and welcome to Scicomp! I think your question is best addressed by the PETSc mailing list. Have you tried submitting your question to them? $\endgroup$ – Paul Aug 11 '13 at 22:22

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