On Mon, Jan 24, 2011 at 3:32 PM, Rongliang Chen <span dir="ltr"><<a href="mailto:rongliang.chan@gmail.com">rongliang.chan@gmail.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hi,<br><br>I face a problem on the LU factorization. When I use the PETSC's default LU factorization, my code does not converge for KSP. </blockquote><div><br></div><div>This is no enough information. Note that if you use this in parallel, it is just BlokcJacobi LU and thus it is not</div>
<div>surprising that it does not converge.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">When I use superlu with command line "-sub_pc_factor_mat_solver_package superlu", it said </blockquote>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
"[43]PETSC ERROR: ------------------------------------------------------------------------<br>[43]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation, probably memory access out of range<br>[43]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger<br>
[43]PETSC ERROR: or see <a href="http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Signal[43]PETSC" target="_blank">http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Signal[43]PETSC</a> ERROR: or try <a href="http://valgrind.org" target="_blank">http://valgrind.org</a> on GNU/linux and Apple Mac OS X to find memory corruption errors<br>
[43]PETSC ERROR: likely location of problem given in stack below<br>[43]PETSC ERROR: --------------------- Stack Frames ------------------------------------<br>[43]PETSC ERROR: Note: The EXACT line numbers in the stack are not available,<br>
[43]PETSC ERROR: INSTEAD the line number of the start of the function<br>[43]PETSC ERROR: is given.<br>[43]PETSC ERROR: [43] MatLUFactorNumeric_SuperLU line 121 src/mat/impls/aij/seq/superlu/superlu.c<br>[43]PETSC ERROR: [43] MatLUFactorNumeric line 2575 src/mat/interface/matrix.c<br>
............................<br> "<br></blockquote><div><br></div><div>Please confirm that you have the latest patch level. If so, send the matrix in PETSc binary format to <a href="mailto:petsc-maint@mcs.anl.gov">petsc-maint@mcs.anl.gov</a></div>
<div>along with the precise solver options and output of -ksp_view.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">When I use superlu_dist, my code converges well, but I found that the compute time is very high. What's maybe the problem? Thanks.<br>
</blockquote><div><br></div><div>This is not surprising either. Sparse LU factorization can be expensive.</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<br>Regards,<br><font color="#888888"><br>Rongliang<br>
</font></blockquote></div><br><br clear="all"><br>-- <br>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener<br>