On Mon, Sep 7, 2009 at 2:01 AM, Klaij, Christiaan <span dir="ltr"><<a href="mailto:C.Klaij@marin.nl">C.Klaij@marin.nl</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Matt,<br>
<br>
Thanks for your answer!<br>
<br>
dummy is defined as a PETSc integer inside MyKSPConverged, so why can't I set it to 0? I know it's not useful because it's just a dummy and nothing happens with it, but setting it shouldn't crash the code, right? Also, if setting it changes the basic definition of PETSC_NULL_OBJECT shouldn't you get a SEGV as well, or at least some kind of trouble?<br>
</blockquote><div><br>dummy is something <b>you passed in</b> earlier in the code, and you passed in something that should not change. I<br>do not know why you are getting an SEGV (I do not get one), but I do know you should not change this for the<br>
code to function correctly.<br><br> Matt<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Chris<br>
<br>
<br>
<br>
Message: 5<br>
Date: Fri, 4 Sep 2009 10:49:25 -0500<br>
From: Matthew Knepley <<a href="mailto:knepley@gmail.com">knepley@gmail.com</a>><br>
Subject: Re: dummy in MyKSPConverged<br>
To: PETSc users list <<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>><br>
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On Fri, Sep 4, 2009 at 10:35 AM, Klaij, Christiaan <<a href="mailto:C.Klaij@marin.nl">C.Klaij@marin.nl</a>> wrote:<br>
<br>
> Hello,<br>
><br>
> With the new version 3.0.0-p8, if I assign a value to the dummy in<br>
> MyKSPConverged at the end of src/ksp/ksp/examples/tutorials/ex2f.F, I get a<br>
> segmentation fault (this didn't happen with version 2.3.3-p13). Any idea<br>
> why?<br>
><br>
<br>
1) I do not get a SEGV<br>
<br>
2) You should not be setting this at all. You pass in PETSC_NULL_OBJECT,<br>
which means you are changing the definition of that<br>
basic thing in PETSc. This can produce undefined results.<br>
<br>
Matt<br>
<br>
<br>
> $ tail ex2f.F<br>
> else<br>
> flag = 0<br>
> endif<br>
> ierr = 0<br>
> dummy = 0<br>
><br>
> end<br>
> $ ./ex2f -my_ksp_convergence<br>
> [0]PETSC ERROR:<br>
> ------------------------------------------------------------------------<br>
> [0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation,<br>
> probably memory access out of range<br>
> [0]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger<br>
> [0]PETSC ERROR: or see<br>
> <a href="http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Signal%5B0%5DPETSC" target="_blank">http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Signal[0]PETSC</a><br>
> ERROR: or try <a href="http://valgrind.org" target="_blank">http://valgrind.org</a> on linux or man libgmalloc on Apple to<br>
> find memory corruption errors<br>
> [0]PETSC ERROR: likely location of problem given in stack below<br>
> [0]PETSC ERROR: --------------------- Stack Frames<br>
> ------------------------------------<br>
> [0]PETSC ERROR: Note: The EXACT line numbers in the stack are not<br>
> available,<br>
> [0]PETSC ERROR: INSTEAD the line number of the start of the function<br>
> [0]PETSC ERROR: is given.<br>
> [0]PETSC ERROR: [0] GMREScycle line 133 src/ksp/ksp/impls/gmres/gmres.c<br>
> [0]PETSC ERROR: [0] KSPSolve_GMRES line 228 src/ksp/ksp/impls/gmres/gmres.c<br>
> [0]PETSC ERROR: [0] KSPSolve line 308 src/ksp/ksp/interface/itfunc.c<br>
> [0]PETSC ERROR: --------------------- Error Message<br>
> ------------------------------------<br>
> [0]PETSC ERROR: Signal received!<br>
> [0]PETSC ERROR:<br>
> ------------------------------------------------------------------------<br>
> [0]PETSC ERROR: Petsc Release Version 3.0.0, Patch 8, Fri Aug 21 14:02:12<br>
> CDT 2009<br>
> [0]PETSC ERROR: See docs/changes/index.html for recent updates.<br>
> [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.<br>
> [0]PETSC ERROR: See docs/index.html for manual pages.<br>
> [0]PETSC ERROR:<br>
> ------------------------------------------------------------------------<br>
<br>
dr. ir. Christiaan Klaij<br>
CFD Researcher<br>
Research & Development<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>
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