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<p class="MsoNormal">Hello petsc-users,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I would like to check convergence against the infinity norm, so I defined my own convergence test routine with KSPSetConvergenceTest. (I understand that it may be computationally expensive.)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I would like to do this with the “ibcgs” method. When I use KSPBuildResidual and calculate the NORM_2 against the output vector, I get a value that differs from the 2-norm that gets passed into the convergence test function. However, when
I switch to the “gcr” method, the value I calculate matches the function input value.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is the KSPBuildResidual function only compatible with a subset of the KSPType methods? If I want to evaluate convergence against the infinity norm, do I need to set KSPSetInitialGuessNonzero and continually re-start the solver with a lower
tolerance values until I get a satisfactory value of the infinity norm?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Greg<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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