<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Tue, Dec 12, 2017 at 11:30 AM, Alexander Lindsay <span dir="ltr"><<a href="mailto:alexlindsay239@gmail.com" target="_blank">alexlindsay239@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr" style="font-size:12.8px">I'm not using any hand-coded Jacobians.</div></div></blockquote><div><br></div><div>This looks to me like the rules for FormFunction/Jacobian() are being broken. If the residual function</div><div>depends on some third variable, and it changes between calls independent of the solution U, then</div><div>the stored Jacobian could look wrong, but one done every time on the fly might converge.</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr" style="font-size:12.8px"><div>Case 1 options: -snes_fd -pc_type lu</div><div><br></div><div><span class=""><span class="m_-7017120415024906329gmail-im"><div>0 Nonlinear |R| = 2.259203e-02</div><div> 0 Linear |R| = 2.259203e-02</div></span></span><div> 1 Linear |R| = 7.821248e-11</div><span class=""><span class="m_-7017120415024906329gmail-im"><div> 1 Nonlinear |R| = 2.258733e-02</div><div> 0 Linear |R| = 2.258733e-02</div></span></span><div> 1 Linear |R| = 5.277296e-11</div><span class=""><span class="m_-7017120415024906329gmail-im"><div> 2 Nonlinear |R| = 2.258733e-02</div><div> 0 Linear |R| = 2.258733e-02</div></span></span><div> 1 Linear |R| = 5.993971e-11</div><span class=""><span class="m_-7017120415024906329gmail-im">Nonlinear solve did not converge due to DIVERGED_LINE_SEARCH iterations 2</span></span></div><div><br></div><div>Case 2 options: -snes_fd -snes_mf_operator -pc_type lu</div><div><br></div><div><span class=""><span class="m_-7017120415024906329gmail-im"><div> 0 Nonlinear |R| = 2.259203e-02</div><div> 0 Linear |R| = 2.259203e-02</div></span></span><div> 1 Linear |R| = 2.258733e-02</div><div> 2 Linear |R| = 3.103342e-06</div><div> 3 Linear |R| = 6.779865e-12</div><div> 1 Nonlinear |R| = 7.497740e-06</div><div> 0 Linear |R| = 7.497740e-06</div><div> 1 Linear |R| = 8.265413e-12</div><div> 2 Nonlinear |R| = 7.993729e-12</div><div>Nonlinear solve converged due to CONVERGED_FNORM_RELATIVE iterations 2</div></div></div><div class="m_-7017120415024906329gmail-yj6qo m_-7017120415024906329gmail-ajU" style="margin:2px 0px 0px;font-size:12.8px"><div id="m_-7017120415024906329gmail-:2o0" class="m_-7017120415024906329gmail-ajR"><img class="m_-7017120415024906329gmail-ajT" src="https://ssl.gstatic.com/ui/v1/icons/mail/images/cleardot.gif" style="opacity:0.3"></div></div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Dec 12, 2017 at 9:12 AM, zakaryah . <span dir="ltr"><<a href="mailto:zakaryah@gmail.com" target="_blank">zakaryah@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div style="font-size:small">When you say "Jacobians are bad" and "debugging the Jacobians", do you mean that the hand-coded Jacobian is wrong? In that case, why would you be surprised that the finite difference Jacobians, which are "correct" to approximation error, perform better? Otherwise, what does "Jacobians are bad" mean - ill-conditioned? Singular? Not symmetric? Not positive definite?</div></div>
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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>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</div><div><br></div><div><a href="http://www.caam.rice.edu/~mk51/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div>
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