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<div style="font-family:Helvetica,Arial;font-size:13px; ; ">Hi Ellen,</div>
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<div style="font-family:Helvetica,Arial;font-size:13px; ; ">It looks like you’re using the old unconstrained CG code. This will be deprecated in the near future in favor of the newer bound-constrained CG algorithm (TAOBNCG) that can also solve unconstrained
problems when the user does not specify any bounds on the problem. </div>
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<div style="font-family:Helvetica,Arial;font-size:13px; ; ">The newer TAOBNCG algorithm implements a preconditioner that significantly improves the scaling of the search direction and helps the line search accept the unit step length most of the time. I would
recommend making sure that you’re on PETSc version 3.11 or newer, and then switching to this with “-tao_type bncg”. You will not need to change any of your code to do this. If you still fail to converge, please send a new log with the new algorithm and we
can evaluate the next steps.</div>
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<div class="gmail_signature">—
<div>Alp Dener</div>
<div>Postdoctoral Researcher</div>
<div>Argonne National Laboratory</div>
<div>https://www.anl.gov/profile/alp-dener</div>
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<p class="airmail_on">On February 26, 2020 at 6:01:34 PM, Ellen Price (<a href="mailto:ellen.price@cfa.harvard.edu">ellen.price@cfa.harvard.edu</a>) wrote:</p>
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<div>Hi Jed,</div>
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<div>Thanks for getting back to me! Here's the output for my CG config. Sorry it's kind of a lot.<br>
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<div>Ellen<br>
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<div dir="ltr" class="gmail_attr">On Wed, Feb 26, 2020 at 12:43 PM Jed Brown <<a href="mailto:jed@jedbrown.org">jed@jedbrown.org</a>> wrote:<br>
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Could you share output for your current configuration with -tao_monitor -tao_ls_monitor -tao_view?<br>
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"Ellen M. Price" <<a href="mailto:ellen.price@cfa.harvard.edu" target="_blank">ellen.price@cfa.harvard.edu</a>> writes:<br>
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> Hello PETSc users!<br>
><br>
> I am using Tao for an unconstrained minimization problem. I have found<br>
> that CG works better than the other types for this application. After<br>
> about 85 iterations, I get an error about line search failure. I'm not<br>
> clear on what this means, or how I could mitigate the problem, and<br>
> neither the manual nor FAQ give any guidance. Can anyone suggest things<br>
> I could try to help the method converge? I have function and gradient<br>
> info, but no Hessian.<br>
><br>
> Thanks,<br>
> Ellen Price<br>
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