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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">Dear Matt,
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">I wanted to try out NGMRES. I am using options [1] from your tutorial slides. This works fine with SNES ex19, but fails with error [2] when
I use my code. When I use my code with SNES options “-snes_type newtonls -snes_linesearch_type l2” it runs fine.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">Is this me doing something wrong in FormJacobian or what could this be? Is there a SNES example with MatSetValuesStencil I could try with NGMRES?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">Thank you!<br>
Henrik<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[1]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">-snes_type ngmres -npc_snes_max_it 1 -snes_converged_reason -npc_snes_type fas -npc_fas_coarse_snes_converged_reason -npc_fas_levels_snes_type
newtonls -npc_fas_levels_snes_max_it 6 -npc_fas_levels_snes_linesearch_type basic -npc_fas_levels_snes_max_linear_solve_fail 30 -npc_fas_levels_ksp_max_it 20 -npc_fas_levels_snes_converged_reason -npc_fas_coarse_snes_linesearch_type basic<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[2]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: Null argument, when expecting valid pointer<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: Null Object: Parameter # 1<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: Petsc Release Version 3.8.2, unknown
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: /rwthfs/rz/cluster/work/hb111949/Descramble/1D_Model/steam/JUBE/ngmres/debug/shem_fw64gnu_steam.x on a arch-linux2-c-debug
named linuxbmc0004.rz.RWTH-Aachen.DE by hb111949 Thu Nov 30 14:35:56 2017<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: Configure options --download-fblaslapack --with-cc=mpicc --with-fc=mpif90 --with-cxx=mpicxx --download-hypre --download-superlu_dist
--download-suitesparse --download-scalapack --download-blacs --download-hdf5 --download-parmetis --download-metis --with-debugging=1 --download-mumps<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: #1 ISLocalToGlobalMappingApply() line 639 in /rwthfs/rz/cluster/home/hb111949/Code/petsc/src/vec/is/utils/isltog.c<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: #2 MatSetValuesLocal() line 2139 in /rwthfs/rz/cluster/home/hb111949/Code/petsc/src/mat/interface/matrix.c<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US">[0]PETSC ERROR: #3 MatSetValuesStencil() line 1550 in /rwthfs/rz/cluster/home/hb111949/Code/petsc/src/mat/interface/matrix.c<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New"">--
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New"">Dipl.-Math. Henrik Büsing<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New"">Institute for Applied Geophysics and Geothermal Energy<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New"">E.ON Energy Research Center<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Courier New"">RWTH Aachen University<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New"">------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New"">Mathieustr. 10 | Tel +49 (0)241 80 49907<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New"">52074 Aachen, Germany | Fax +49 (0)241 80 49889<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New"">------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New"">http://www.eonerc.rwth-aachen.de/GGE<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New"">hbuesing@eonerc.rwth-aachen.de<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New"">------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Von:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Matthew Knepley [mailto:knepley@gmail.com]
<br>
<b>Gesendet:</b> 07 November 2017 12:54<br>
<b>An:</b> Buesing, Henrik <hbuesing@eonerc.rwth-aachen.de><br>
<b>Cc:</b> petsc-users <petsc-users@mcs.anl.gov><br>
<b>Betreff:</b> Re: [petsc-users] Newton methods that converge all the time<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Tue, Nov 7, 2017 at 4:19 AM, Buesing, Henrik <<a href="mailto:hbuesing@eonerc.rwth-aachen.de" target="_blank">hbuesing@eonerc.rwth-aachen.de</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Courier New"">Dear all,
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Courier New""> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">I am solving a system of nonlinear, transient PDEs. I am using Newton’s method in every time step to solve the nonlinear algebraic
equations. Of course, Newton’s method only converges if the initial guess is sufficiently close to the solution.
<br>
<br>
This is often not the case and Newton’s method diverges. Then, I reduce the time step and try again. This can become prohibitively costly, if the time steps get very small. I am thus looking for variants of Newton’s method, which have a bigger convergence radius
or ideally converge all the time. </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New""> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">I tried out the pseudo-timestepping described in
<a href="http://www.mcs.anl.gov/petsc/petsc-current/src/ts/examples/tutorials/ex1f.F.html" target="_blank">
http://www.mcs.anl.gov/petsc/petsc-current/src/ts/examples/tutorials/ex1f.F.html</a>.
</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">However, this does converge even worse. I am seeing breakdown when I have phase changes (e.g. liquid to two-phase).
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New""> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">I was under the impression that pseudo-timestepping should converge better. Thus, my question:
<br>
<br>
Am I doing something wrong or is it possible that Newton’s method converges and pseudo-timestepping does not?<br>
<br>
Thank you for any insight on this. </span><o:p></o:p></p>
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<p class="MsoNormal">Hi Hendrik,<o:p></o:p></p>
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<p class="MsoNormal">I would try using NGMRES as a nonlinear preconditioner. I have an example in my tutorial slides for using it with SNES ex19.<o:p></o:p></p>
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<p class="MsoNormal">I hope this will work because I suspect that around the phase boundary Newton directions are noisy, since sometimes you<o:p></o:p></p>
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<p class="MsoNormal">step into the other phase. NGMRES takes a few directions (you set the m) and then picks the best one.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> Hopefully this helps,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> Matt<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">Henrik</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">--
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">Dipl.-Math. Henrik Büsing</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">Institute for Applied Geophysics and Geothermal Energy</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">E.ON Energy Research Center</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-family:"Courier New"">RWTH Aachen University</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Courier New""><a href="https://maps.google.com/?q=Mathieustr.+10&entry=gmail&source=g">Mathieustr. 10</a> | Tel
<a href="tel:+49%20241%208049907" target="_blank">+49 (0)241 80 49907</a></span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Courier New"">52074 Aachen, Germany | Fax
<a href="tel:+49%20241%208049889" target="_blank">+49 (0)241 80 49889</a></span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Courier New""><a href="http://www.eonerc.rwth-aachen.de/GGE" target="_blank">http://www.eonerc.rwth-aachen.de/GGE</a></span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Courier New""><a href="mailto:hbuesing@eonerc.rwth-aachen.de" target="_blank">hbuesing@eonerc.rwth-aachen.de</a></span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">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<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><a href="http://www.caam.rice.edu/~mk51/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><o:p></o:p></p>
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