<html>Thank you for your quick response.<br /><br />Yes, i'm running in parallel, I'm just asking for 2 eigenvalues and I'm not doing any factorization.<br /><br />My problem is taking so long because I have implemented the time stepping-exponential transformation: my MatMult() function for computing vectors of the Krylov subspace calls the Direct Numerical Simulation code for compressible Navier-Stokes equations to which I'm linking the stability code.<br />Therefore, each MatMult() call takes very long, and I cannot save the converged eigenvectors for the restart beacause there won't be any converged eigenvectors yet when the job is killed.<br />That's why I thought that the only thing I could save was the computed krylov subspace.<br /><br />Victoria<br /><br /><br /><br />Il giorno Venerdi, Agosto 21, 2020 12:42 CEST, "Jose E. Roman" <jroman@dsic.upv.es> ha scritto:<br /> <blockquote type="cite" cite="34111C3C-F81A-41A4-8747-5602F8E7B348@dsic.upv.es">Why is your problem taking so long? Are you running in parallel? Is your computation doing a factorization of a matrix? Are you getting slow convergence? How many eigenvalues are you computing? Note that Krylov-Schur is not intended for computing a large percentage of eigenvalues, if you do so then you might get large overheads unless you tune the EPSSetDimensions() parameters (mpd).<br /><br />EPSSetInitialSpace() is intended to provide an initial guess, which in Krylov-Schur is a single vector, so in this case you would not pass the Krylov subspace from a previous run.<br /><br />A possible scheme for restarting is to save the eigenvectors computed so far, then pass them in the next run via EPSSetDeflationSpace() to avoid recomputing them. You can use a custom stopping criterion as in https://slepc.upv.es/documentation/current/src/eps/tutorials/ex29.c.html to stop before the job is killed, then save the converged eigenvectors (or EPSGetInvariantSubspace() if the problem is nonsymmetric).<br /><br />Jose<br /><br /><br />> El 21 ago 2020, a las 11:56, ROLANDI Laura victoria <Laura-victoria.ROLANDI@isae-supaero.fr> escribió:<br />><br />> Dear SLEPc developers,<br />><br />> I'm using the Krylov Schur EPS and I have a question regarding a command.<br />><br />> Is there a way for having access and saving the krylov subspace during the EPSSolve call?<br />><br />> I inizialize the solver using the function EPSSetInitialSpace(eps,1, v0), where v0 is a specific vector, but after 24 hours of calculation my job has to end even if the EPSSolve hasn't finished yet.<br />> Which function should I use for saving the computed Krylov subspace and its dimention n during the process, in order to restart the calculation from it by using EPSsetInitialSpace(eps,n, Krylov-Subspace)?<br />><br />> Thank you very much,<br />> Victoria<br /> </blockquote><br /><br /><br />--<br /><meta charset="utf-8" /><title></title><style type="text/css">th, td, p{padding: 0px;margin: 0px;color: rgb(18,35,114); font-family: Arial, Helvetica, sans-serif;vertical-align: top;}
.sig_nom {font-size: 12px;font-weight:bold;text-align="left";}
.sig_prenom {text-transform: none;}
.sig_container {padding-right:57px;}
.sig_standard {font-size: 11px;}
.sig_entete {margin-right: 10px;}
a {color:rgb(0,170,255); text-decoration: none}
table { padding-top:57px;padding-bottom:57px;border-spacing: 0px;}</style>---<table border="0"><tbody><tr><td class="sig_container"><p class="sig_nom"><span class="sig_prenom">Laura victoria</span> ROLANDI</p><p class="sig_standard">Doctorant - Doctorat ISAE-SUPAERO Doctorat 1<br />laura-victoria.rolandi@isae-supaero.fr</p></td><td class="sig_container"><p class="sig_standard"><a href="https://www.isae-supaero.fr">https://www.isae-supaero.fr</a><br />Institut Supérieur de l'Aéronautique et de l'Espace<br />10, avenue Edouard Belin - BP 54032<br />31055 Toulouse Cedex 4<br />France</p></td></tr><tr height="57px"><td colspan="4" style="border-bottom:1px solid rgb(210,230,255)"> </td></tr><tr><td colspan="2"> </td><td class="sig_container" colspan="2"><p class="sig_standard">Suivez l'ISAE-SUPAERO sur les réseaux sociaux / Follow the ISAE-SUPAERO on the social media<br /><a href="https://fr-fr.facebook.com/isae.supaero">Facebook</a> <a href="https://twitter.com/isae_officiel">Twitter</a> <a href="https://www.linkedin.com/school/isae/">LinkedIn</a> <a href="https://www.youtube.com/user/ISAEcom">Youtube</a> <a href="https://www.instagram.com/isae_supaero/">Instagram</a></p></td></tr></tbody></table></html>