Hello, Matt
The results of the parallel and the serial are identical by the
"-ksp_rtol 1.0e-15 -ksp_converged_reason -ksp_monitor_true_residual".
I will make a carefulanalysis of these parameters next day because it is
late night here now.
Thanks again. Jim
>? 2012-05-26 22:26:20?"Matthew Knepley" <knepley at gmail.com> ???
>On Sat, May 26, 2012 at 2:22 PM, w_ang_temp <w_ang_temp at 163.com> wrote:
>Hello,Matt
> Thanks again.
> What you said("Use -ksp_type preonly -pc_type lu") means that I should use
> a direct solver.And I am puzzled.
>Okay, you want to remove variables from the investigation. You say there is a
>difference between
>the parallel and serial solve. We do this all the time, so it is not a bug. It
>is an issue of understanding.
>First, take away the tolerance issues:
> -ksp_rtol 1.0e-15 -ksp_converged_reason -ksp_monitor_true_residual
>and send output of the serial and parallel run.
> Matt
> (1)I think this problem (single processor is ok and more than one are
> problematic)is typical,but I cannot
>find useful infomation both in the manual and the petsc-users.So can you give
>me some explanation for this
>phenomenon.
> (2)When I use -pc_type lu,the error message is "Matrix format mpiaij does
> not have a built-in PETSc LU!".
> (3)The manual says that "This approach prevents the user from the
> unexpected surprise of having a
>corrupted matrix after a linear solve"(P72).So do you mean the problem of mine
>is here?
> (4)Generally I want to use the iterative approach other than the direct
> method.
> As a beginne r,I have to learn more about the manual.And also I think an
> experienced senior will be a more
> useful help for me because I have gotten stuck on this problem for more than
> a week.
> Thanks. Jim
>At 2012-05-26 20:17:42,"Matthew Knepley" <knepley at gmail.com> wrote:
>Use -ksp_type preonly -pc_type lu.
> Matt
--
What most experimenters take for granted before they begin their experiments is
infinitely more interesting than any results to which their experiments lead.
-- Norbert Wiener
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