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<p style="margin-top:0;margin-bottom:0">1) My experience is that this kind of bug or sudden death (everything is fine till suddenly something is broken) is very difficult to debug/fix. I looked at your txt files and could not give any quick comments. Maybe
PETSc developers have better idea on this.</p>
<p style="margin-top:0;margin-bottom:0">2) I do have successful experience on reducing time step size when PETSc fails solving or my own piece of code throws an exception. If you are interested, I can share them.</p>
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<p style="margin-top:0;margin-bottom:0">-Ling</p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> petsc-users <petsc-users-bounces@mcs.anl.gov> on behalf of Rahul Samala <srahul_05@yahoo.co.in><br>
<b>Sent:</b> Wednesday, August 29, 2018 8:36:58 AM<br>
<b>To:</b> PETSc Users List<br>
<b>Subject:</b> [petsc-users] Problem with SNES convergence</font>
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<div>Hello PetSc users,</div>
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<div>1) I have problem with SNES convergence. I call SNESSolve in a time loop and use the inbuilt Jacobian feature. The code works fine for about 5380 time steps after which it breaks down. The solution till that point looks fine. I have used newtonls of
type l2. (newtontr and others aren't working). Since I have used <span>inbuilt Jacobian feature and the code worked for about 5000 time steps I don't understand the reason for failure, is it an incorrect function evaluation? Attached are the outputs with
-pc_type lu and ilu along with -snes_linesearch_type l2 -snes_converged_reason -snes_monitor -snes_view -ksp_converged_reason -ksp_monitor_true_residual</span></div>
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<div><span>2) How to get hold of failure signal, like Nonlinear solve <span>DIVERGED_MAX_IT or
<span>DIVERGED_LINEAR_SOLVE so that whenever it occurs I can use a reduced time step and see if the code converges.</span></span></span></div>
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<div><span><span><span>Thank you,</span></span></span></div>
<div><span><span><span>Rahul.<br>
</span></span></span></div>
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