<div dir="ltr"><div>The solver did not diverge.</div><div>It was the line search that was not able to make further progress in minimizing the 2-norm of the residual.</div><div>This is common in nonlinear solvers. It would help if you tell us what you are trying to solve.</div><div><div>Note that at the first step, your residual norm is already 1.e-6. What kind of accuracy do you want?<br></div><div><br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Il giorno gio 7 set 2023 alle ore 13:08 Karthikeyan Chockalingam - STFC UKRI via petsc-users <<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>> ha scritto:<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 class="msg477101460960849173">
<div lang="EN-GB" style="overflow-wrap: break-word;">
<div class="m_477101460960849173WordSection1">
<p class="MsoNormal">Hello,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">The non-linear solution diverged. The final solution seems right and I believe the Jacobian is correct (not 100% certain).
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I am not sure if I doing something wrong in the solver setting.
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span></span><span style="color:black">0 SNES Function norm 3.890991210938e-03<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">0 KSP Residual norm 9.037762538598e+00<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">1 KSP Residual norm 2.120375403775e-01<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">2 KSP Residual norm 5.155439334511e-03<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">3 KSP Residual norm 1.394364169369e-04<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">4 KSP Residual norm 9.233543407204e-06<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">Linear solve converged due to CONVERGED_RTOL iterations 4<u></u><u></u></span></p>
<p class="m_477101460960849173p2"><span style="color:black"><u></u> <u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Using full step: fnorm 3.890991210938e-03 gnorm 7.701511565083e-06<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">1 SNES Function norm 7.701511565083e-06<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">0 KSP Residual norm 5.630229687829e-03<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">1 KSP Residual norm 1.030475601271e-04<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">2 KSP Residual norm 2.576454714319e-06<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">3 KSP Residual norm 6.669316846898e-08<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">4 KSP Residual norm 3.215810984829e-09<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black"> </span>
</span><span style="color:black">Linear solve converged due to CONVERGED_RTOL iterations 4<u></u><u></u></span></p>
<p class="m_477101460960849173p2"><span style="color:black"><u></u> <u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: gnorm after quadratic fit 1.805500533481e-05<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 2.563759884284e-05 lambda=3.0804668685096816e-02<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 3.332721829751e-05 lambda=3.0804668685096817e-03<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 4.102754045833e-05 lambda=3.0804668685096822e-04<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 4.872893294880e-05 lambda=3.0804668685096822e-05<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 5.643043250787e-05 lambda=3.0804668685096822e-06<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 6.413194279696e-05 lambda=3.0804668685096827e-07<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 7.183345417492e-05 lambda=3.0804668685096828e-08<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 7.953496567312e-05 lambda=3.0804668685096829e-09<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 8.723647719173e-05 lambda=3.0804668685096831e-10<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 9.493798871875e-05 lambda=3.0804668685096832e-11<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 1.026395002516e-04 lambda=3.0804668685096835e-12<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: Cubic step no good, shrinking lambda, current gnorm 1.103410117889e-04 lambda=3.0804668685096835e-13<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: unable to find good step length! After 12 tries<span class="m_477101460960849173apple-converted-space"> </span><u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span class="m_477101460960849173apple-converted-space"><span style="color:black">
</span></span><span style="color:black">Line search: fnorm=7.7015115650831560e-06, gnorm=1.1034101178892401e-04, ynorm=6.2052357872955976e-03, minlambda=9.9999999999999998e-13, lambda=3.0804668685096835e-13, initial slope=-5.9313318983096354e-11<u></u><u></u></span></p>
<p class="m_477101460960849173p1"><span style="color:black">Nonlinear solve did not converge due to DIVERGED_LINE_SEARCH iterations 1<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thank you for your help.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Kind regards,<u></u><u></u></p>
<p class="MsoNormal">Karthik.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<div>
<div>
<p class="MsoNormal"><span>-- <u></u><u></u></span></p>
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<div>
<p class="MsoNormal"><b><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:rgb(45,45,98)">Dr. Karthik Chockalingam<u></u><u></u></span></b></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">Senior Research Software Engineer</span><span style="font-size:10.5pt;color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">High Performance Systems Engineering Group</span><span style="font-size:10.5pt;color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">Hartree Centre | Science and Technology Facilities Council</span><span style="font-size:10.5pt;color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:rgb(33,33,33)"><a href="mailto:karthikeyan.chockalingam@stfc.ac.uk" target="_blank"><span style="color:rgb(5,99,193)">karthikeyan.chockalingam@stfc.ac.uk</span></a></span><span style="color:rgb(33,33,33)"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12pt;font-family:"Times New Roman",serif;color:black"> </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:rgb(65,65,65)"> </span><span style="color:rgb(33,33,33)"><u></u><u></u></span></p>
<p class="MsoNormal"><b><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:rgb(65,65,65)"> </span></b><span style="font-size:12pt;font-family:"Times New Roman",serif;color:rgb(31,73,125)"><img border="0" width="254" height="116" style="width: 2.6458in; height: 1.2083in;" id="m_477101460960849173Picture_x0020_1" src="cid:image001.png@01D9E17A.4E8AA8B0" alt="signature_3970890138"></span><span style="color:rgb(33,33,33)"><u></u><u></u></span></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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</div></blockquote></div><br clear="all"><br><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature">Stefano</div>