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Hi everyone,</div>
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The first max time it is trying to reach is 1.0e-12 s, and the initial dt is set to 1.0e-12 s from the commandline options. I believe it's not a formatting issue and that the dt is actually set somewhere to 0 s because that's why the step is rejected.</div>
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Best,</div>
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Sophie</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Barry Smith <bsmith@petsc.dev><br>
<b>Sent:</b> Friday, December 13, 2024 14:21<br>
<b>To:</b> Blondel, Sophie <sblondel@utk.edu>; Jed Brown <jed@jedbrown.org>; Zhang, Hong <hongzhang@anl.gov>; Emil Constantinescu <emconsta@anl.gov><br>
<b>Cc:</b> petsc-users@mcs.anl.gov <petsc-users@mcs.anl.gov>; xolotl-psi-development@lists.sourceforge.net <xolotl-psi-development@lists.sourceforge.net><br>
<b>Subject:</b> Re: [petsc-users] "-ts_exact_final_time matchstep" leads to DIVERGED_STEP_REJECTED</font>
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Hm, what is the final time you are stepping towards in this run?
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<div> There is something wrong with the adapt code since it seems to start with a dt of 0 but then tries "adapting" several times, but it could be the </div>
<div>monitor function does not correctly format numbers smaller than 1.e-12 and it is just using truly small dt.</div>
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<div> Jed, Hong, Emil?</div>
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<div> Barry</div>
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<div>On Dec 10, 2024, at 11:08 AM, Blondel, Sophie <sblondel@utk.edu> wrote:</div>
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Good morning Barry,</div>
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Attached are the updated files, there is more useful information in them.</div>
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Cheers,</div>
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Sophie</div>
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<font face="Calibri, sans-serif" style="font-size:11pt"><b>From:</b><span class="x_x_Apple-converted-space"> </span>Blondel, Sophie via Xolotl-psi-development <<a href="mailto:xolotl-psi-development@lists.sourceforge.net">xolotl-psi-development@lists.sourceforge.net</a>><br>
<b>Sent:</b><span class="x_x_Apple-converted-space"> </span>Monday, December 9, 2024 17:29<br>
<b>To:</b><span class="x_x_Apple-converted-space"> </span>Barry Smith <<a href="mailto:bsmith@petsc.dev">bsmith@petsc.dev</a>><br>
<b>Cc:</b><span class="x_x_Apple-converted-space"> </span><a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a><span class="x_x_Apple-converted-space"> </span><<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>>;<span class="x_x_Apple-converted-space"> </span><a href="mailto:xolotl-psi-development@lists.sourceforge.net">xolotl-psi-development@lists.sourceforge.net</a><span class="x_x_Apple-converted-space"> </span><<a href="mailto:xolotl-psi-development@lists.sourceforge.net">xolotl-psi-development@lists.sourceforge.net</a>><br>
<b>Subject:</b><span class="x_x_Apple-converted-space"> </span>Re: [Xolotl-psi-development] [petsc-users] "-ts_exact_final_time matchstep" leads to DIVERGED_STEP_REJECTED</font>
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Hi Barry,</div>
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I hope you are doing well.</div>
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Attached are the output. To give a little more context, this is a "new" way of running the code where multiple instances are created and communicate together every few time steps (like coupling the code with itself in memory). Here there are 3 instances that
each have a separate TS object, plus one "main" instance that doesn't solve anything but compute rates to exchange between the other instances.</div>
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Cheers,</div>
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Sophie</div>
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<div id="x_x_x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt"><b>From:</b><span class="x_x_Apple-converted-space"> </span>Barry Smith <<a href="mailto:bsmith@petsc.dev">bsmith@petsc.dev</a>><br>
<b>Sent:</b><span class="x_x_Apple-converted-space"> </span>Monday, December 9, 2024 15:12<br>
<b>To:</b><span class="x_x_Apple-converted-space"> </span>Blondel, Sophie <<a href="mailto:sblondel@utk.edu">sblondel@utk.edu</a>><br>
<b>Cc:</b><span class="x_x_Apple-converted-space"> </span><a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a><span class="x_x_Apple-converted-space"> </span><<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>>;<span class="x_x_Apple-converted-space"> </span><a href="mailto:xolotl-psi-development@lists.sourceforge.net">xolotl-psi-development@lists.sourceforge.net</a><span class="x_x_Apple-converted-space"> </span><<a href="mailto:xolotl-psi-development@lists.sourceforge.net">xolotl-psi-development@lists.sourceforge.net</a>><br>
<b>Subject:</b><span class="x_x_Apple-converted-space"> </span>Re: [petsc-users] "-ts_exact_final_time matchstep" leads to DIVERGED_STEP_REJECTED</font>
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<div>On Dec 9, 2024, at 2:56 PM, Blondel, Sophie via petsc-users <<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>> wrote:</div>
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Hi,</div>
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I am trying to understand a strange behavior I'm encountering: when running my application with "-ts_exact_final_time stepover" everything goes well, but when I switch to "matchstep" I get DIVERGED_STEP_REJECTED before the first time step is finished.</div>
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<div> This is in the very first time-step in TSSolve? </div>
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<div> Please run with -ts_monitor and send all the output (best for a short time interval and do it twice once with <span style="font-family:Calibri,Helvetica,sans-serif; font-size:12pt">-ts_exact_final_time stepover and once with exact.</span></div>
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<div><span style="font-family:Calibri,Helvetica,sans-serif; font-size:12pt"> Barry</span></div>
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I tried increasing the maximum number of rejections and it just takes longer to diverge, and if I set the value to "unlimited" it is basically an infinite loop.</div>
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Is there a way to check why is the step rejected? Could the "matchstep" option change tolerances somewhere that would cause that behavior?</div>
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Let me know if I should provide more information.</div>
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Best,</div>
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Sophie Blondel</div>
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