[petsc-dev] Problem with conjugate gradient solver

[Anush Krishnan]

> Message: 6
> Date: Mon, 23 Aug 2010 18:40:34 -0500
> From: Barry Smith <bsmith at mcs.anl.gov>
> Subject: Re: [petsc-dev] Problem with conjugate gradient solver
> To: For users of the development version of PETSc
>        <petsc-dev at mcs.anl.gov>
> Message-ID: <6432610F-F243-4C9C-AB6A-0944221AE18D at mcs.anl.gov>
> Content-Type: text/plain; charset=us-ascii
>
>
> On Aug 23, 2010, at 2:31 PM, Anush Krishnan wrote:
>
> > Hi,
> >
> > I was trying to compile and run the example file
> $PETSC_DIR/src/ksp/pc/examples/tutorials/ex3.c, which demonstrates PETSc's
> preconditioned conjugate gradient solver for a system of linear equations.
> After compiling, running make runex3 is supposed to throw up the error
> "Divergence because of indefinite preconditioner" and running make runex3_pd
> is supposed to work and give the correct solution. But instead I get the
> error "Other kind of divergence: this should not happen." for the latter. Is
> there some bug in the code, or are there any other options that need to be
> set?
>
>   Hmm, worked for me.
>
>    Please hg pull; hg update then rebuild PETSc and run the make runex3
> runex3_pd again and send the output. I added to that example what reason it
> did have to maybe help determine the problem. Or you can run the example
> with the options given in the makefile and also the option
> -ksp_converged_reason
>

I've attached the outputs I got with runex3 and runex3_pd (1 and 2
respectively. I commented out the statements after the execute commands to
prevent deletion of the generated output files). This was on revision 16788.

Thanks,
Anush


>
>
>   Barry
>
> >
> > Thanks,
> > Anush
>
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