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<p class="MsoNormal"><span style="font-size:11.0pt">Hi all,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Can someone please help me understand the output of the following two outputs using ‘-snes_view’?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Option 1:<o:p></o:p></span></p>
<p class="p1"><span class="s1">SNES Object: 1 MPI process</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">type: newtonls</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">maximum iterations=15, maximum function evaluations=10000</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">tolerances: relative=1e-08, absolute=1e-50, solution=1e-08</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">total number of linear solver iterations=5</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">total number of function evaluations=14</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">norm schedule ALWAYS</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space"><span style="color:#00B050">  </span>
</span><span class="s1"><span style="color:#00B050">Jacobian is built using finite differences with coloring</span></span><span style="color:#00B050"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Option 2:<o:p></o:p></span></p>
<p class="p1"><span class="s1">SNES Object: 1 MPI process</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">type: newtonls</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">maximum iterations=50, maximum function evaluations=10000</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">tolerances: relative=1e-08, absolute=1e-50, solution=1e-08</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">total number of linear solver iterations=8</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">total number of function evaluations=17</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space">  </span><span class="s1">norm schedule ALWAYS</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space"><span style="color:#00B050">  </span>
</span><span class="s1"><span style="color:#00B050">Jacobian is applied matrix-free with differencing</span></span><span style="color:#00B050"><o:p></o:p></span></p>
<p class="p1"><span class="apple-converted-space"><span style="color:#00B050">  </span>
</span><span class="s1"><span style="color:#00B050">Preconditioning Jacobian is built using finite differences with coloring</span></span><span style="color:#00B050"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Does it mean that<o:p></o:p></span></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph" style="margin-left:-15.75pt;mso-list:l0 level1 lfo1">
<span style="font-size:11.0pt">Option 1 uses Newton’s method, such that J du = b is solved with J being explicitly constructed?<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:-15.75pt;mso-list:l0 level1 lfo1">
<span style="font-size:11.0pt">Option 2 uses matrix free method, such that J du = b is solved with  J v ~ (F(u + dv) – F(u)) / h when needed, e.g., in a Krylov method.<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">-Ling<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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