<div dir="ltr">Please send the output with -st_ksp_view and -st_ksp_monitor and we can start to debug it.<div><br></div><div>You mentioned that B is not symmetric. I assume it is elliptic (diffusion). Where does the asymmetry come from?</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Oct 2, 2017 at 9:39 AM, Wenbo Zhao <span dir="ltr"><<a href="mailto:zhaowenbo.npic@gmail.com" target="_blank">zhaowenbo.npic@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><span class=""><div>Matt,<br></div>Thanks for your reply.<br></span><div class="gmail_extra">For the defalt option doesnt work firstly( -st_ksp_type gmres -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 1), I tried to test those options.</div><span class="HOEnZb"><font color="#888888"><div class="gmail_extra"><br></div><div class="gmail_extra">Wenbo<br></div></font></span><div><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Oct 2, 2017 at 9:08 PM, Matthew Knepley <span dir="ltr"><<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><span class="m_1885042015433017079gmail-">On Mon, Oct 2, 2017 at 8:30 AM, Wenbo Zhao <span dir="ltr"><<a href="mailto:zhaowenbo.npic@gmail.com" target="_blank">zhaowenbo.npic@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><div>Matt</div><div><br></div><div>Because I am not clear about what will happen using 'preonly' for large scale problem. <br></div></div></div></blockquote><div><br></div></span><div>The size of the problem has nothing to do with 'preonly'. All it means is to apply a preconditioner without a Krylov solver.</div><span class="m_1885042015433017079gmail-"><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><div>It seems to use a direct solver from below, <br><a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPPREONLY.html" target="_blank">http://www.mcs.anl.gov/petsc/p<wbr>etsc-current/docs/manualpages/<wbr>KSP/KSPPREONLY.html</a></div></div></div></blockquote><div><br></div></span><div>However, I still cannot understand why you would change the default?</div><div><br></div><div> Matt</div><div><div class="m_1885042015433017079gmail-h5"><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><div><br></div>Thanks!<br></div>Wenbo<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Oct 2, 2017 at 5:09 PM, Matthew Knepley <span dir="ltr"><<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><span>On Sun, Oct 1, 2017 at 9:53 PM, Wenbo Zhao <span dir="ltr"><<a href="mailto:zhaowenbo.npic@gmail.com" target="_blank">zhaowenbo.npic@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Matt,<br>Thanks for your reply.<br>It DOES make no sense for this problem.<br>But I am not clear about the 'preonly' option. Which solver is used in preonly? I wonder if 'preonly' is suitable for large scale problem such as 400,000,000 unknowns.<br>So I tried 'gmres' option and found these error messages.<br></div></blockquote><div><br></div></span><div>I mean, why are you setting this at all. Just do not set the coarse solver. The default should work fine.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div><div class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455h5"><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Could you give me some suggestions?<br><br>Thanks.<br><br>Wenbo<br><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Oct 2, 2017 at 12:34 AM, Matthew Knepley <span dir="ltr"><<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><span>On Sun, Oct 1, 2017 at 6:49 AM, Wenbo Zhao <span dir="ltr"><<a href="mailto:zhaowenbo.npic@gmail.com" target="_blank">zhaowenbo.npic@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Hi,<br><br>I met some questions when I use PETSC/SLEPC to solve two-group neutron diffusion equations with finite difference method. The grid is 3*3*3, when DOF on each points is 2. So the matrix size is 54*54.<br>It is generalized eigenvalue problem Ax=\lamda Bx, where B is diagonally dominant matrix but not symmetry.<br>EPS is set as below,<br> ierr = EPSSetProblemType(eps,EPS_GNHE<wbr>P);CHKERRQ(ierr);¬<br> ierr = EPSSetWhichEigenpairs(eps,EPS_<wbr>LARGEST_REAL);CHKERRQ(ierr);¬<br><br>Krylovschur is used as eps sovler. GAMG is used as PC.<br>I tried agg_nsmooths and mg_coarse_ksp_type. Only non-smooths and preonly is OK.<br></div></div></blockquote><div><br></div></span><div>Why are you setting the coarse solver. This makes no sense.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div><div class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455m_-8305666638070075194m_3153904134462254503h5"><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><br>Test 1<br>$ make NCORE=1 runkr_nonsmooth <br>mpirun -n 1 ./step-41 \<br> -st_ksp_type gmres \<br> -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 0 \<br> -st_ksp_view -mata AMAT.dat -matb BMAT.dat \<br> -st_mg_coarse_ksp_type preonly -st_mg_coarse_ksp_monitor \<br> -eps_nev 1 -eps_ncv 10 -eps_monitor -log_view > log_nonsmooth 2>&1<br> <br>Test 2<br>$ make NCORE=1 runkr_smooth <br>mpirun -n 1 ./step-41 \<br> -st_ksp_type gmres \<br> -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 1 \<br> -st_ksp_view -mata AMAT.dat -matb BMAT.dat \<br> -st_mg_coarse_ksp_type preonly -st_mg_coarse_ksp_monitor \<br> -eps_nev 1 -eps_ncv 10 -eps_monitor -log_view > log_smooth 2>&1<br>makefile:43: recipe for target 'runkr_smooth' failed<br>make: *** [runkr_smooth] Error 91<br><br>Test 3<br>$ make NCORE=1 runkr_gmres <br>mpirun -n 1 ./step-41 \<br> -st_ksp_type gmres \<br> -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 0 \<br> -st_ksp_view -mata AMAT.dat -matb BMAT.dat \<br> -st_mg_coarse_ksp_type gmres -st_mg_coarse_ksp_monitor -st_mg_coarse_ksp_rtol 1.0e-6 \<br> -eps_nev 1 -eps_ncv 10 -eps_monitor -log_view > log_gmres 2>&1<br>makefile:59: recipe for target 'runkr_gmres' failed<br>make: *** [runkr_gmres] Error 91<br><br>Log files were attched.<br>The matrix file were also attched as AMAT.dat and BMAT.dat.<br><br>Is it correct? Or something wrong with my code or commad-line?<br><br>Thanks!<span class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455m_-8305666638070075194m_3153904134462254503m_5044481091402600956HOEnZb"><font color="#888888"><br><br></font></span></div><span class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455m_-8305666638070075194m_3153904134462254503m_5044481091402600956HOEnZb"><font color="#888888">Wenbo<br></font></span></div>
</blockquote></div></div></div><span class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455m_-8305666638070075194m_3153904134462254503HOEnZb"><font color="#888888"><br><br clear="all"><span class="m_1885042015433017079gmail-m_-7838439549008716278HOEnZb"><font color="#888888"><span class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455m_-8305666638070075194HOEnZb"><font color="#888888"><div><br></div>-- <br><div class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455m_-8305666638070075194m_3153904134462254503m_5044481091402600956gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>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</div><div><br></div><div><a href="http://www.caam.rice.edu/%7Emk51/" target="_blank">https://www.cse.buffalo.edu/~k<wbr>nepley/</a><br></div></div></div></div></div>
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</font></span></blockquote></div></div></div><span class="m_1885042015433017079gmail-m_-7838439549008716278HOEnZb"><font color="#888888"><div><div class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455h5"><br><br clear="all"><div><br></div>-- <br><div class="m_1885042015433017079gmail-m_-7838439549008716278m_-3221509347772759455m_-8305666638070075194gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>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</div><div><br></div><div><a href="http://www.caam.rice.edu/%7Emk51/" target="_blank">https://www.cse.buffalo.edu/~k<wbr>nepley/</a><br></div></div></div></div></div>
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</blockquote></div></div></div><div><div class="m_1885042015433017079gmail-h5"><br><br clear="all"><div><br></div>-- <br><div class="m_1885042015433017079gmail-m_-7838439549008716278gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>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</div><div><br></div><div><a href="http://www.caam.rice.edu/%7Emk51/" target="_blank">https://www.cse.buffalo.edu/~k<wbr>nepley/</a><br></div></div></div></div></div>
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