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Jed,<br>
<br>
I tried LU, the result is the same (attached). The matrix is
recognized as a symmetric, even though I put in the code:<br>
ierr = MatSetOption(A,MAT_SYMMETRIC,PETSC_FALSE);<br>
ierr = MatSetOption(A,MAT_SPD,PETSC_FALSE);<br>
<br>
Seems like internal check? <br>
I checked positive-definiteness of the matrix in matlab (using
[L,p,s] = chol(A); test) and it's not SPD. <br>
So it seems like PaStiX is not very robust. This case is not one
inch close to the bad cases I used MUMPS with. <br>
<br>
Regards,<br>
Alexander<br>
<br>
On 28.12.2011 14:11, Jed Brown wrote:
<blockquote
cite="mid:CAM9tzSnjQ1yKot9AChW_yNiX1WCrAwZOCi1bf5Q=L9Hc2xXduA@mail.gmail.com"
type="cite">
<div class="gmail_quote">On Wed, Dec 28, 2011 at 07:02, Alexander
Grayver <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:agrayver@gfz-potsdam.de">agrayver@gfz-potsdam.de</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000">Hi Jed,<br>
If you mean input parameters they are as following:<br>
-ksp_view -ksp_monitor -mat_type mpisbaij -ksp_type preonly
-pc_type cholesky -pc_factor_mat_solver_package pastix
-mat_pastix_verbose 2 <br>
<div class="im"> <br>
<blockquote type="cite">
<div class="gmail_quote">
<div> </div>
<blockquote class="gmail_quote" style="margin: 0pt 0pt
0pt 0.8ex; border-left: 1px solid rgb(204, 204,
204); padding-left: 1ex;">
<div>The output is attached.<br>
The matrix is SPD and has condition number of 16,
there should be no problem.<br>
I use petsc-dev.<br>
How could I figure out where is the problem?</div>
</blockquote>
</div>
<br>
<div>This sounds like a small example matrix. Can you
-ksp_view_binary and send us the output file
('binaryoutput').</div>
</blockquote>
<br>
</div>
Maybe it was too preliminary to say that it is positive
definite since CG diverges with reason
DIVERGED_INDEFINITE_MAT,</div>
</blockquote>
<div><br>
</div>
<div>Oh, I also see in the PaStiX output that it is reporting an
error (but just a number). If you run with
-ksp_converged_reason, it should say that it diverged. You
should always run with -ksp_converged_reason
-ksp_monitor_true_residual when investigating whether a solver
is converging. From code, call KSPGetConvergedReason().</div>
<div> </div>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> however GMRES with
default parameters converges successfully.<br>
Matrix is ~200000x200000, not so small, but zipped occupies
4.5 Mb. Shall I send it?</div>
</blockquote>
</div>
<br>
<div>Try solving with LU instead. It sounds like Cholesky is just
breaking down, maybe because it does a slightly different method
than the other direct solver packages.</div>
</blockquote>
<br>
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