<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr"></div><div dir="ltr"><br></div><div dir="ltr"><br><blockquote type="cite">On 18 Nov 2022, at 2:32 PM, Karthikeyan Chockalingam - STFC UKRI via petsc-users <petsc-users@mcs.anl.gov> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
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<p class="MsoNormal">Hello,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I would like to move from code to using options. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:Menlo;color:#3900A0;mso-fareast-language:EN-GB"> KSP</span><span style="font-size:9.0pt;font-family:Menlo;color:black;mso-fareast-language:EN-GB"> ksp;</span><span style="font-size:10.0pt;color:black;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:Menlo;color:black;mso-fareast-language:EN-GB"> </span><span style="font-size:9.0pt;font-family:Menlo;color:#3900A0;mso-fareast-language:EN-GB">PC</span><span style="font-size:9.0pt;font-family:Menlo;color:black;mso-fareast-language:EN-GB">
pc;</span><span style="font-size:10.0pt;color:black;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:Menlo;color:#6C36A9;mso-fareast-language:EN-GB"> KSPCreate(PETSC_COMM_WORLD, &ksp);</span><span style="font-size:10.0pt;color:black;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:Menlo;color:black;mso-fareast-language:EN-GB"> </span><span style="font-size:9.0pt;font-family:Menlo;color:#6C36A9;mso-fareast-language:EN-GB">KSPSetOperators</span><span style="font-size:9.0pt;font-family:Menlo;color:black;mso-fareast-language:EN-GB">(ksp,
A, A);<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:Menlo;color:black;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="color:black">I tried using PetscOptionsSetValue as below</span><span style="font-size:9.0pt;font-family:Menlo;color:black;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:Menlo;color:black;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="p1"><span class="apple-converted-space"> </span>ierr = <span class="s1">
PetscOptionsSetValue</span>(<span class="s2"><b>NULL</b></span>,<span class="s3">"-ksp_type"</span>,
<span class="s3">"cg"</span>); <span class="s4">CHKERRQ</span>(ierr);<o:p></o:p></p>
<p class="p1"><span class="apple-converted-space"> </span>ierr = <span class="s1">
PetscOptionsSetValue</span>(<span class="s2"><b>NULL</b></span>,<span class="s3">"-pc_type"</span>,
<span class="s3">"jacobi"</span>); <span class="s4">CHKERRQ</span>(ierr);<o:p></o:p></p>
<p class="p1"><span class="apple-converted-space"> </span>ierr = <span class="s1">
PetscOptionsSetValue</span>(<span class="s2"><b>NULL</b></span>, <span class="s3">
"-ksp_monitor"</span>, <span class="s2"><b>NULL</b></span>);<span class="s4">CHKERRQ</span>(ierr);<o:p></o:p></p>
<p class="p1"><span class="apple-converted-space"> </span>ierr = <span class="s1">
PetscOptionsSetValue</span>(<span class="s2"><b>NULL</b></span>, <span class="s3">
"-ksp_view"</span>, <span class="s2"><b>NULL</b></span>);<span class="s4">CHKERRQ</span>(ierr);<o:p></o:p></p>
<p class="p2"><span class="apple-converted-space"> </span><span class="s5">ierr =
</span><span class="s1">PetscOptionsSetValue</span><span class="s5">(</span><span class="s2"><b>NULL</b></span><span class="s5">,
</span>"-ksp_monitor_true_residual"<span class="s5">, </span><span class="s2"><b>NULL</b></span><span class="s5">);</span><span class="s4">CHKERRQ</span><span class="s5">(ierr);</span><o:p></o:p></p>
<p class="p1"><span class="apple-converted-space"> </span>ierr = <span class="s1">
PetscOptionsSetValue</span>(<span class="s2"><b>NULL</b></span>, <span class="s3">
"-ksp_converged_reason"</span>, <span class="s2"><b>NULL</b></span>);<span class="s4">CHKERRQ</span>(ierr);<o:p></o:p></p>
<p class="p1"><o:p> </o:p></p>
<p class="p1"><span class="apple-converted-space"> </span><span class="s1">KSPSolve</span>(ksp, b, x);<o:p></o:p></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;color:black;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal">But I believe none of the string flags where picked up by PETSc. What am I missing?</p></div></div></blockquote><div><br></div><div>KSPSetFromOptions()</div><div><br></div><div>Thanks,</div><div>Pierre</div><br><blockquote type="cite"><div dir="ltr"><div class="WordSection1">
<p class="MsoNormal">Thank you for your help.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Kind regards,<o:p></o:p></p>
<p class="MsoNormal">Karthik.<o:p></o:p></p>
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