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<p class="MsoNormal"><span style="font-size:11.0pt">Although I haven’t tried yet. Does it make sense and should it work to change the code this way?<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:8.0pt;font-family:Monaco">================================================================</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">PetscErrorCode SNESFormFunction(SNES, Vec, Vec, void*);</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">double my_function();</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">================================================================</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">double my_function()</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">{</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> if (all_good)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">return 1;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> else</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> {</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">throw 199;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">return 0;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> }</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">PetscErrorCode SNESFormFunction(SNES snes, Vec u, Vec r, void* ctx)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">{<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Try<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> {</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">my_value = my_function();<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Catch (int err)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> return PETSC_ERR_NOT_CONVERGED;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> }</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> // compute residuals<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> return PETSC_SUCCESS;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">int main(int argc, char **argv)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">{</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Initialize_PETSc();</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> double dt = 1, dt_min = 0.001;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> while (dt > dt_min)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> {</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">SNESSolve(AppCtx.snes, NULL, AppCtx.u);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">SNESGetConvergedReason(AppCtx.snes, &(AppCtx.snes_converged_reason));<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">if (not_converged)<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco"> dt *= 0.5;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> }</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> PetscFinalize();</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">================================================================</span><span style="font-size:12.0pt"><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"><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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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">petsc-users <petsc-users-bounces@mcs.anl.gov> on behalf of Zou, Ling via petsc-users <petsc-users@mcs.anl.gov><br>
<b>Date: </b>Wednesday, October 1, 2025 at 9:33</span><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black"> </span><span style="font-size:12.0pt;color:black">AM<br>
<b>To: </b>PETSc <petsc-users@mcs.anl.gov><br>
<b>Subject: </b>[petsc-users] Proper way for exception handling<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Hi,</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">After updating to PETSc 3.23 (from a quite old version, ~3.8), I found that my old way of exception handling not working any more, on my Mac.</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I would like to learn the proper way to handle exceptions in PETSc code.</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Here is my pseudo code:</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">================================================================</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">PetscErrorCode SNESFormFunction(SNES, Vec, Vec, void*);</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">double my_function();</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">================================================================</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">double my_function()</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">{</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> if (all_good)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">return 1;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> else</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> {</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">throw 199;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">return 0;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> }</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">PetscErrorCode SNESFormFunction(SNES snes, Vec u, Vec r, void* ctx)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">{</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> double my_value = my_function();</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> // compute residuals</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">int main(int argc, char **argv)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">{</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Initialize_PETSc();</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> double dt = 1, dt_min = 0.001;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> while (dt > dt_min)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> {</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">try</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">{</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco"> SNESSolve(AppCtx.snes, NULL, AppCtx.u);</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">catch (int err)</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">{</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco"> dt *= 0.5;</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:19.5pt"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> }</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> PetscFinalize();</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">}</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">================================================================</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">This piece of logic used to work well, but now giving me the following error:</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Current time (the starting time of this time step) = 0.. </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> NL step = 0, SNES Function norm = 8.60984E+03</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black;background:yellow">libc++abi: terminating due to uncaught exception of type int</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black;background:yellow">Abort trap: 6</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Q1: why this exception catch logic not working any more?</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Q2: is there any good example of PETSc exception handling I can follow?</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Best,</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">-Ling</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
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