[petsc-users] Field split questions

[Jed Brown]

On Sun, Aug 26, 2012 at 8:42 PM, Colin McAuliffe <cjm2176 at columbia.edu>wrote:

> Im getting segmentation faults when I call PetscSectionSetChart, gdb is
> telling me this:
>
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> Reason: 13 at address: 0x0000000000000000
> 0x00000001005f9585 in PetscTrFreeDefault (aa=0x4008000000000000, line=296,
> function=0x1016bd470 "PetscSectionSetChart",
>     file=0x1016bcbb8 "/Users/christina/Desktop/**
> COLIN/Work/petsc-dev/src/vec/**vec/impls/seq/vsection.c", dir=0x1016bca50
> "")
>     at /Users/christina/Desktop/**COLIN/Work/petsc-dev/src/sys/**
> memory/mtr.c:279
> 279       if (head->classid != CLASSID_VALUE) {
> (gdb) ba
> #0  0x00000001005f9585 in PetscTrFreeDefault (aa=0x4008000000000000,
> line=296, function=0x1016bd470 "PetscSectionSetChart",
>     file=0x1016bcbb8 "/Users/christina/Desktop/**
> COLIN/Work/petsc-dev/src/vec/**vec/impls/seq/vsection.c", dir=0x1016bca50
> "")
>     at /Users/christina/Desktop/**COLIN/Work/petsc-dev/src/sys/**
> memory/mtr.c:279
> #1  0x000000010075120b in PetscSectionSetChart (s=0x102e06910, pStart=1,
> pEnd=0)
>     at /Users/christina/Desktop/**COLIN/Work/petsc-dev/src/vec/**
> vec/impls/seq/vsection.c:296
> #2  0x00000001006e99f3 in petscsectionsetchart_ (s=0x7fff5fbfee38,
> pStart=0x10165bc1c, pEnd=0x10165bc18, __ierr=0x7fff5fbfee4c)
>     at /Users/christina/Desktop/**COLIN/Work/petsc-dev/src/vec/**
> vec/impls/seq/ftn-auto/**vsectionf.c:148
> #3  0x0000000100020c4c in setfs_ (fsind=<value temporarily unavailable,
> due to optimizations>,
>     numfields=<value temporarily unavailable, due to optimizations>) at
> umacr8.F:96
>

It would help to have a non-optimized trace. Have you run this under
valgrind?


>
>
> Also, calling:
>
>       call PetscSectionCreate(PETSC_COMM_**WORLD,sec,ierr)
>       call PetscSectionGetChart(sec,**pStart,pEnd,ierr)
>
> returns pStart = 1 and pEnd = 0. Shouldn't PetscSectionCreate set pStart
> and pEnd to -1 and -1?
>
> I am a bit stumped here, any idea what is going on?
>
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