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Thanks a lot for your explanation. Could you please share your petsc code to test this ? Thanks, Xiaodong On Fri, Jun 7, 2024 at 10: 12 PM Barry Smith <bsmith@ petsc. dev> wrote: If I run with -pc_type lu it solves the system If I run with
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<div dir="ltr">Thanks a lot for your explanation. <br><div>Could you please share your petsc code to test this ?</div><div><br></div><div>Thanks,</div><div><br></div><div>Xiaodong </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jun 7, 2024 at 10:12 PM Barry Smith <<a href="mailto:bsmith@petsc.dev">bsmith@petsc.dev</a>> wrote:<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><div><br></div> If I run with -pc_type lu it solves the system<div><br></div><div> If I run with the default (ILU) -ksp_monitor_true_residual -ksp_converged_reason it does not converge. In fact, it makes no real progress to the solution.</div><div><br></div><div> It is always important to use KSPGetConvergedReason() or -ksp_converged_reason or -ksp_error_if_not_converged to check that the solver has actually converged.</div><div><br></div><div> If I run with <span style="font-family:Menlo;font-size:14px">-ksp_gmres_restart 100 it converges in 75 iterations.</span></div><div><span style="font-family:Menlo;font-size:14px"><br></span></div><div><span style="font-family:Menlo;font-size:14px"> Barry</span></div><div><span style="font-family:Menlo;font-size:14px"><br></span></div><div><br></div><div><br id="m_3843710384836975978lineBreakAtBeginningOfMessage"><div><br><blockquote type="cite"><div>On Jun 7, 2024, at 8:03 PM, neil liu <<a href="mailto:liufield@gmail.com" target="_blank">liufield@gmail.com</a>> wrote:</div><br><div><div dir="ltr" id="m_3843710384836975978pfptBanner5zbfu2d" 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Message Is From an External Sender</div><div id="m_3843710384836975978pfptBanner5zbfu2d" style="writing-mode:unset;font-family:Arial,sans-serif;font-feature-settings:unset;font-kerning:unset;font-size:12px;font-stretch:unset;font-variant-alternates:unset;font-variant-caps:unset;font-variant-east-asian:unset;font-variant-ligatures:unset;font-variant-numeric:unset;font-weight:unset;text-orientation:unset;zoom:unset;letter-spacing:unset;background-blend-mode:unset;background-image:unset;background-position:unset;background-repeat:unset;background-size:unset;border-collapse:unset;border:unset;box-sizing:unset;break-after:unset;break-before:unset;break-inside:unset;caption-side:unset;clear:unset;columns:unset;column-fill:unset;column-gap:unset;column-rule:unset;column-span:unset;empty-cells:unset;float:unset;image-orientation:unset;isolation:unset;line-break:unset;line-height:18px;list-style:unset;mix-blend-mode:unset;object-fit:unset;object-position:unset;outline:unset;overflow:unset;quotes:unset;table-layout:unset;text-align:unset;text-align-last:unset;text-decoration:unset;text-emphasis:unset;text-indent:unset;text-overflow:unset;text-transform:unset;text-underline-position:unset;vertical-align:unset;white-space:unset;word-break:unset;border-spacing:unset;word-spacing:unset;background-clip:unset;background-origin:unset;text-combine-upright:unset;display:block;opacity:unset;background-color:rgb(208,216,220);border-radius:unset;height:unset;margin-bottom:unset;margin-left:unset;margin-right:unset;max-height:unset;max-width:unset;min-height:unset;min-width:unset;padding:unset;width:unset;margin-top:2px">This message came from outside your organization.</div></div><div style="height:0px;clear:both;display:block;line-height:0;font-size:0.01px"></div></div><div dir="ltr" style="font-family:Helvetica;font-size:18px;font-style:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none"><div dir="ltr">Dear Petsc developers, <br><div><br></div><div>I am using Petsc to solve a complex system ,AX=B.</div><div><br></div><div>A is complex and B is real. </div><div><br></div><div>And the petsc was configured with </div><div>Configure options --download-mpich --download-fblaslapack=1 --with-cc=gcc --with-cxx=g++ --with-fc=gfortran --download-triangle --with-scalar-type=complex<br></div><div><br></div><div>A and B were also imported to matlab and the same system was solved.</div><div>The direct and iterative solver in matlab give the same result, which are quite different from the result from Petsc. </div><div>A and B are attached. x from petsc is also attached. I am using only one processor. </div><div><br></div><div>It is weird. </div><div><br></div><div>Thanks a lot.</div><div><br></div><div>Xiaodong </div></div></div><span id="m_3843710384836975978cid:f_lx5cpn480"><A.m></span><span id="m_3843710384836975978cid:f_lx5cqk7y1"><xPetsc.m></span><span id="m_3843710384836975978cid:f_lx5cqrm92"><B.m></span></div></blockquote></div><br></div></div></blockquote></div>