<div dir="ltr">Hello guys,<div><br></div><div>Today I am about to write a custom convergence test for KSP doing the following job:</div><div><br></div><div>- if the number of ksp iterations is less than a given threshold, iterate until that threshold is met</div><div>- if the number of ksp iterations is bigger than the threshold, use the standard convergence checks.</div><div><br></div><div>As far as I understood from the examples, this is the function I need to use:</div><div><pre width="80" style="color:rgb(0,0,0)"><a href="https://petsc.org/main/manualpages/KSP/KSPSetConvergenceTest/">KSPSetConvergenceTest</a>(ksp,MyKSPConverged,0,PETSC_NULL_FUNCTION,ierr)</pre><pre width="80" style="color:rgb(0,0,0)"><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal">With MyKSPConverge a subroutine (I am in fortran) where my custom checks are implemented.</div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><br></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal">Here is how I have coded  <span style="color:rgb(0,0,0)">MyKSPConverged:</span></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><span style="color:rgb(0,0,0)"><i><br></i></span></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><i>    subroutine MyKSPConverged(ksp,n,rnorm,flag,dummy,ierr)<br><br>       KSP              ksp<br>       PetscErrorCode ierr<br>       PetscInt n,dummy<br>       KSPConvergedReason flag<br>       PetscReal rnorm<br><br>       if (n>1) then<br>         call KSPConvergedDefault(ksp, n, rnorm, flag, ierr)<br>       else<br>         flag = 0<br>       endif<br>       ierr = 0<br><br>    end subroutine MyKSPConverged</i><span style="color:rgb(0,0,0)"><br></span></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><br></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal">However I get this error: </div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal">[0]PETSC ERROR: KSPSolve has not converged, reason DIVERGED_DTOL<br></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal">which I believe to be triggered by <span class="gmail-Lm gmail-ng gmail-Vs" style="background-image:url("data:image/svg+xml;base64,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");background-repeat:repeat-x;border-bottom:2px solid transparent;outline:none"><i>KSPConvergedDefault. </i>This is odd, as this simulation converge perfectly if I comment ou my dodgy convergence test.</span></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><i><span class="gmail-Lm gmail-ng gmail-Vs" style="background-image:url("data:image/svg+xml;base64,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");background-repeat:repeat-x;border-bottom:2px solid transparent;outline:none"><br></span></i></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><span class="gmail-Lm gmail-ng gmail-Vs" style="background-image:url("data:image/svg+xml;base64,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");background-repeat:repeat-x;border-bottom:2px solid transparent;outline:none"><i>Do you have any advice for me?</i></span></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><span class="gmail-Lm gmail-ng gmail-Vs" style="background-image:url("data:image/svg+xml;base64,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");background-repeat:repeat-x;border-bottom:2px solid transparent;outline:none"><i><br></i></span></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><span class="gmail-Lm gmail-ng gmail-Vs" style="background-image:url("data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSI0IiBoZWlnaHQ9IjUiPgogIDxkZWZzPgogICAgICA8cGF0dGVybiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIGlkPSJzcGVsbGluZy16aWd6YWciIHdpZHRoPSI0IiBoZWlnaHQ9IjUiIHBhdHRlcm5Vbml0cz0ib2JqZWN0Qm91bmRpbmdCb3giIHBhdHRlcm5Db250ZW50VW5pdHM9InVzZXJTcGFjZU9uVXNlIiB4PSIwIiB5PSIwIj4KICAgICAgICA8cGF0aCBkPSJNIDAgMyBMIDIgMSBMIDQgMyIgc3Ryb2tlPSIjNDI4NUY0IiBzdHJva2Utd2lkdGg9IjEiIGZpbGw9Im5vbmUiIHN0cm9rZS1saW5lY2FwPSJzcXVhcmUiLz4KICAgICAgPC9wYXR0ZXJuPgogICAgPC9kZWZzPgogIDxyZWN0IHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgZmlsbD0idXJsKCNzcGVsbGluZy16aWd6YWcpIiBoZWlnaHQ9IjEwMCUiIHdpZHRoPSIxMDAlIiAvPgo8L3N2Zz4=");background-repeat:repeat-x;border-bottom:2px solid transparent;outline:none"><i>thank you! </i></span></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><span class="gmail-Lm gmail-ng gmail-Vs" style="background-image:url("data:image/svg+xml;base64,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");background-repeat:repeat-x;border-bottom:2px solid transparent;outline:none"><i><br></i></span></div><div style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;white-space:normal"><span class="gmail-Lm gmail-ng gmail-Vs" style="background-image:url("data:image/svg+xml;base64,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");background-repeat:repeat-x;border-bottom:2px solid transparent;outline:none"><i> </i></span><br></div>
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