Jinquan:<div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="EN-US" link="blue" vlink="purple"><div><div>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I have a strange observation on using MatLUFactorNumeric() for dense matrices at different order N.  Here is the situation I have:</span></p>
</div></div></div></blockquote><div><br></div><div>Superlu and mumps are sparse direct solvers, not for dense</div><div>matrices. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p><u></u><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><span>1.<span style="font:7.0pt "Times New Roman"">      
</span></span></span><u></u><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I use ./src/mat/tests/ex137.c as an example to direct PETSc in </span></p></div></div></div>
</blockquote><div>    petsc-3.3/src/mat/examples/tests/ex137.c is a</div><div>"Tests MatCreateMPISBAIJWithArrays()."</div><div>Which version of petsc do you use?                                      </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div lang="EN-US" link="blue" vlink="purple"><div><div><p><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">selecting superLU-dist and mumps.  The calling sequence is
<u></u><u></u></span></p>
<p style="margin-left:1.0in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">MatGetOrdering(A,…)<u></u><u></u></span></p>
<p style="margin-left:1.0in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">MatGetFactor(A,…)<u></u><u></u></span></p>
<p style="margin-left:1.0in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">MatLUFactorSymbolic(F, A,…)<u></u><u></u></span></p>
<p style="margin-left:1.0in"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">MatLUFactorNumeric</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">(F, A,…)<u></u><u></u></span></p>

<p style="margin-left:1.0in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">MatSolve(F,b,x)<u></u><u></u></span></p>
<p><u></u><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><span>2.<span style="font:7.0pt "Times New Roman"">      
</span></span></span><u></u><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I have three dense matrices A at three different dimensions: N=75, 2028 and 21180. 
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<p><u></u><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><span>3.<span style="font:7.0pt "Times New Roman"">      
</span></span></span><u></u><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The calling sequence works for N=75 and 2028.  But when N=21180, the program hanged up when calling
<b>MatLUFactorNumeric</b>(…).  Seemed to be a segmentation fault with the following error message:</span></p></div></div></div></blockquote><div>If your matrices are sparse, i.e., using petsc default aij format,</div><div>
then superlu/mumps should work for  <span style="color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:15px">N=21180.</span></div><div><font color="#1f497d" face="Calibri, sans-serif"><span style="font-size:15px">Start with small number of processors, e.g., 4, 16 etc.</span></font></div>
<div><font color="#1f497d" face="Calibri, sans-serif"><span style="font-size:15px">If superlu_dist hangs, does mumps also hang?</span></font></div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal" style="margin-left:1.0in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Does anybody have similar experience on that?</span></p></div></div></div></blockquote><div><span style="background-color:rgb(255,255,255);color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:15px">Segmentation fault</span> occurs for various reasons.</div>
<div>Give a try to mumps first.</div><div><br></div><div>Hong </div></div>