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Hi Hong,<br>
<br>
Thank. I can test it but it may takes some time to install petsc-dev
on the cluster. I will try more cases to see if I can get this error
on my local machine which is much more convenient for me to test in
debug mode. So far, the error does not occur on my local machine
using the same code, the same petsc-3.6.2 version, the same case and
the same number of processors. The system and petsc configuration is
different.<br>
<br>
Regards,<br>
<br>
Danyang<br>
<br>
<div class="moz-cite-prefix">On 15-12-02 10:26 AM, Hong wrote:<br>
</div>
<blockquote
cite="mid:CAGCphBtN_pV+Y_GP-syOZb_AyANuxBhTZV8Z4gU0nKr-zsBs7g@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">Danyang:</div>
<div class="gmail_quote">It is likely a zero pivot. I'm adding
a feature to petsc. When matrix factorization fails,
computation continues with error information stored in</div>
<div class="gmail_quote">ksp->reason=DIVERGED_PCSETUP_FAILED.</div>
<div class="gmail_quote">For your timestepping code, you may
able to automatically reduce timestep and continue your
simulation.</div>
<div class="gmail_quote"><br>
</div>
<div class="gmail_quote">Do you want to test it? If so, you
need install petsc-dev with my
branch hzhang/matpackage-erroriffpe on your cluster. We may
merge this branch to petsc-master soon.<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"><br>
It's not easy to run in debugging mode as the cluster
does not have petsc installed using debug mode. Restart
the case from the crashing time does not has the
problem. So if I want to detect this error, I need to
start the simulation from beginning which takes hours in
the cluster.<br>
</div>
</blockquote>
<div><br>
</div>
<div>This is why we are adding this new feature. </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> <br>
Do you mean I need to redo symbolic factorization? For
now, I only do factorization once at the first timestep
and then reuse it. Some of the code is shown below. <br>
<br>
if (timestep == 1) then<br>
call
PCFactorSetMatSolverPackage(pc_flow,MATSOLVERMUMPS,ierr)<br>
CHKERRQ(ierr)<br>
<br>
call
PCFactorSetUpMatSolverPackage(pc_flow,ierr)<br>
CHKERRQ(ierr)<br>
<br>
call
PCFactorGetMatrix(pc_flow,a_flow_j,ierr)<br>
CHKERRQ(ierr)<br>
end if<br>
<br>
call KSPSolve(ksp_flow,b_flow,x_flow,ierr)<br>
CHKERRQ(ierr)<br>
</div>
</blockquote>
<div><br>
</div>
<div>I do not think you need to change this part of code. </div>
<div>Does you code check convergence at each time step?</div>
<div><br>
</div>
<div>Hong</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
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<div class="h5"><br>
<br>
<div>On 15-12-02 08:39 AM, Hong wrote:<br>
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<div class="gmail_quote">Danyang :
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">My
code fails due to the error in external
library. It works fine for the previous
2000+ timesteps but then crashes.<br>
<br>
[4]PETSC ERROR: Error in external library<br>
[4]PETSC ERROR: Error reported by MUMPS in
numerical factorization phase: INFO(1)=-1,
INFO(2)=0<br>
</blockquote>
<div> </div>
<div>This simply says an error occurred in
proc[0] during numerical factorization,
which usually either encounter a zeropivot
or run out of memory. Since it is at a
later timesteps, which I guess you reuse
matrix factor, zeropivot might be the
problem.</div>
<div>Is possible to run it in debugging
mode? In this way, mumps would dump out
more information.</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><br>
Then I tried the same simulation on
another machine using the same number of
processors, it does not fail.<br>
</blockquote>
<div>Does this machine have larger memory?</div>
<div><br>
</div>
<div>Hong</div>
</div>
</div>
</div>
</blockquote>
<br>
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