<div dir="ltr"><div>ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);</div><div> <span style="white-space:pre"> </span>ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);</div><div><br></div><div> <span style="white-space:pre"> </span>ierr = VecAssemblyBegin(x);</div><div> <span style="white-space:pre"> </span>ierr = VecAssemblyEnd(x);</div><div><br></div><div> <span style="white-space:pre"> </span>ierr = VecAssemblyBegin(b);</div><div> <span style="white-space:pre"> </span>ierr = VecAssemblyEnd(b);</div><div><br></div><div><br></div><div><span style="white-space:pre"> </span>ierr = MatNullSpaceCreate(PETSC_COMM_WORLD,PETSC_TRUE,0,PETSC_NULL,&nullsp);</div><div> ierr = MatSetNullSpace(A,nullsp); // Petsc-3.8<br></div><div><br></div><div> // KSPSetOperators(ksp,A,A,DIFFERENT_NONZERO_PATTERN);</div><div> KSPSetOperators(ksp,A,A);</div><div><br></div><div><span style="white-space:pre"> </span>KSPSetType(ksp,KSPBCGS);</div><div><br></div><div> KSPSetComputeSingularValues(ksp, PETSC_TRUE);</div><div>#if defined(__HYPRE__)</div><div><span style="white-space:pre"> </span>KSPGetPC(ksp, &pc);</div><div><span style="white-space:pre"> </span>PCSetType(pc, PCHYPRE);</div><div> PCHYPRESetType(pc,"boomeramg");</div><div>#else</div><div><span style="white-space:pre"> </span>KSPSetType(ksp,KSPBCGSL);</div><div><span style="white-space:pre"> </span>KSPBCGSLSetEll(ksp,2);</div><div>#endif /* defined(__HYPRE__) */</div><div><br></div><div> KSPSetFromOptions(ksp);</div><div> KSPSetUp(ksp);</div><div><br></div><div> ierr = KSPSolve(ksp,b,x);<br></div><div><br></div><div><br></div><div>command line </div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Oct 21, 2017 at 5:16 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:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><span class="">On Sat, Oct 21, 2017 at 5:04 PM, Hao Zhang <span dir="ltr"><<a href="mailto:hbcbh1999@gmail.com" target="_blank">hbcbh1999@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">hi, <div><br></div><div>I implemented HYPRE preconditioner for my study due to the fact that without preconditioner, PETSc solver will take thousands of iterations to converge for fine grid simulation.</div><div><br></div><div>with HYPRE, depending on the parallel partition, it will take HYPRE forever to do anything. observation of output file is that the simulation is hanging with no output.</div><div><br></div><div>Any idea what happened? will post snippet of code.</div></div></blockquote><div><br></div></span><div>1) For any question about convergence, we need to see the output of</div><div><br></div><div> -ksp_view_pre -ksp_view -ksp_monitor_true_residual -ksp_converged_reason</div><div><br></div><div>2) Hypre has many preconditioners, which one are you talking about</div><div><br></div><div>3) PETSc has some preconditioners in common with Hypre, like AMG</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><span class=""><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><span class="m_4609829663930822582HOEnZb"><font color="#888888"><div>-- <br><div class="m_4609829663930822582m_8504183156012973410gmail_signature" data-smartmail="gmail_signature">Hao Zhang<br>Dept. of Applid Mathematics and Statistics,<br>Stony Brook University, <br>Stony Brook, New York, 11790</div></div></font></span></div>
</blockquote></span></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><div><br></div>-- <br><div class="m_4609829663930822582gmail_signature" data-smartmail="gmail_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/~mk51/" target="_blank">https://www.cse.buffalo.edu/~<wbr>knepley/</a><br></div></div></div></div></div>
</font></span></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature">Hao Zhang<br>Dept. of Applid Mathematics and Statistics,<br>Stony Brook University, <br>Stony Brook, New York, 11790</div>
</div>