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<p class="MsoNormal">Dear users,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-GB">I have a problem where I step time and repeatedly solve a system with differing rhs.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">At some time step petsc solver returns that initial solution is good enough (converged reason = 2 with 0 iterations done).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I do not expect this behaviour. I use rtol = 0.001, atol=0 and dtol =large number.<o:p></o:p></span></p>
<pre><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></pre>
<pre><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">The manual seems to suggest the criterion is: </span><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">rnorm < MAX (rtol * rnorm_0, abstol) (probably based on preconditioned residual).<o:p></o:p></span></pre>
<pre><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">How could this lead to zero iterations being done? Or is the criterion based on rnorm/bnorm instead (which I found in some reference on the internet concerning petsc and would explain the observed behaviour).<o:p></o:p></span></pre>
<pre><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></pre>
<pre><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Thanks,<o:p></o:p></span></pre>
<pre><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Danny.<o:p></o:p></span></pre>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
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