<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<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); background-color: rgb(255, 255, 255);" class="elementToProof">
I withdraw my question. In trying to put together an example to illustrate the problem, I found that
<span style="color:rgb(36, 36, 36);font-family:"Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif;font-size:14.6667px;background-color:rgb(255, 255, 255);display:inline !important" class="ContentPasted0 elementToProof">
EPSSetInitialSubspace() does indeed "work" - in the sense that the eigenvalue, which decreases monotonically during the calculation, picks up from where the previous run left off. I am not sure why I had previously thought it was otherwise.</span></div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);" class="elementToProof">
<span style="color:rgb(36, 36, 36);font-family:"Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif;font-size:14.6667px;background-color:rgb(255, 255, 255);display:inline !important" class="ContentPasted0 elementToProof"><br>
</span></div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);" class="elementToProof">
<span style="color:rgb(36, 36, 36);font-family:"Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif;font-size:14.6667px;background-color:rgb(255, 255, 255);display:inline !important" class="ContentPasted0 elementToProof">thanks</span></div>
<div class="elementToProof">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div id="Signature">
<div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
<div>% James F. Lutsko, CNLPCS, Universite Libre de Bruxelles,</div>
<div>% Campus Plaine -- CP231 B-1050 Bruxelles, Belgium</div>
<div>% tel: +32-2-650-5997 email: jlutsko@ulb.ac.be</div>
% fax: +32-2-650-5767<br>
</div>
</div>
</div>
</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> Jose E. Roman <jroman@dsic.upv.es><br>
<b>Sent:</b> Tuesday, March 28, 2023 7:43 PM<br>
<b>To:</b> LUTSKO James <Jim.Lutsko@ulb.be><br>
<b>Cc:</b> petsc-users@mcs.anl.gov <petsc-users@mcs.anl.gov><br>
<b>Subject:</b> Re: [petsc-users] Restarting a SLEPC run to refine an eigenvector</font>
<div> </div>
</div>
<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">What do you mean that EPSSetInitialSubspace() does not work? Doesn't it improve convergence with respect to not using it?<br>
<br>
Is your smallest eigenvalue positive? And do you have many eigenvalues close to the smallest one?<br>
<br>
Jose<br>
<br>
<br>
> El 28 mar 2023, a las 17:32, LUTSKO James via petsc-users <petsc-users@mcs.anl.gov> escribió:<br>
> <br>
> Hello,<br>
> I am a complete newbe so sorry if this is answered elsewhere or ill-posed but .. I am trying to get the smallest eigenvector of a large matrix. Since the calculations are very long, I would like to be able to restart my code if I find that the "converged"
eigenvector is not good enough without having to start from scratch. I am currently using the options
<br>
> <br>
> -eps_type jd -eps_monitor -eps_smallest_real -eps_conv_abs -eps_tol 1e-8 -st_ksp_type gmres -st_pc_type jacobi -st_ksp_max_it 40<br>
> <br>
> Is there any way to do this? I have tried using EPSSetInitialSubspace with the stored eigenvector but this does not seem to work.
<br>
> <br>
> thanks <br>
> jim<br>
> <br>
> % James F. Lutsko, CNLPCS, Universite Libre de Bruxelles,<br>
> % Campus Plaine -- CP231 B-1050 Bruxelles, Belgium<br>
> % tel: +32-2-650-5997 email: jlutsko@ulb.ac.be<br>
> % fax: +32-2-650-5767<br>
<br>
</div>
</span></font></div>
</body>
</html>