<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
Than you Matt and Mark, I'll try your suggestions. To configure with hypre can I just use the --download-hypre configure line?</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
That is what I did with suitesparse, very nice.<br>
</div>
<div id="appendonsend"></div>
<hr style="display:inline-block;width:98%" tabindex="-1">
<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Mark Adams <mfadams@lbl.gov><br>
<b>Sent:</b> Monday, June 26, 2023 12:05 PM<br>
<b>To:</b> Vanella, Marcos (Fed) <marcos.vanella@nist.gov><br>
<b>Cc:</b> petsc-users@mcs.anl.gov <petsc-users@mcs.anl.gov><br>
<b>Subject:</b> Re: [petsc-users] SOLVE + PC combination for 7 point stencil (unstructured) poisson solution</font>
<div> </div>
</div>
<div>
<div dir="ltr">I'm not sure what MG is doing with an "unstructured" problem. I assume you are not using DMDA.
<div>-pc_type gamg should work <br>
</div>
<div>I would configure with hypre and try that also: -pc_type hypre</div>
<div><br>
</div>
<div>As Matt said MG should be faster. How many iterations was it taking?</div>
<div>Try a 100^3 and check that the iteration count does not change much, if at all.</div>
<div><br>
</div>
<div>Mark</div>
<div><br>
</div>
</div>
<br>
<div class="x_gmail_quote">
<div dir="ltr" class="x_gmail_attr">On Mon, Jun 26, 2023 at 11:35 AM Vanella, Marcos (Fed) via petsc-users <<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>> wrote:<br>
</div>
<blockquote class="x_gmail_quote" style="margin:0px 0px 0px 0.8ex; border-left:1px solid rgb(204,204,204); padding-left:1ex">
<div class="x_msg-7190608093676655562">
<div dir="ltr">
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Hi, I was wondering if anyone has experience on what combinations are more efficient to solve a Poisson problem derived from a 7 point stencil on a single mesh (serial).</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
I've been doing some tests of multigrid and cholesky on a 50^3 mesh. <b>-pc_type mg</b> takes about 75% more time than
<b>-pc_type cholesky -pc_factor_mat_solver_type cholmod</b> for the case I'm testing.</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
I'm new to PETSc so any suggestions are most welcome and appreciated,</div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Marcos<br>
</div>
</div>
</div>
</blockquote>
</div>
</div>
</body>
</html>