<br><font size=2 face="sans-serif">Dear PETSc developers,</font>
<br>
<br><font size=2 face="sans-serif">As usual your answers are concise and
precise. Thanks a lot for the explanation !</font>
<br><font size=2 face="sans-serif">Browsing the mailing list archive a
bit has made me aware of the native PCGAMG, so we'll update PETSc and give
it a try.</font>
<br>
<br><font size=2 face="sans-serif">Keep up the fantastic work,</font>
<br><font size=2 face="sans-serif">Thomas</font>
<br>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td>
<td><font size=1 face="sans-serif"><b>jedbrown@mcs.anl.gov</b></font>
<br><font size=1 face="sans-serif">Envoyé par : five9a2@gmail.com</font>
<p><font size=1 face="sans-serif">27/06/2013 18:13</font>
<td><font size=1 face="Arial"> </font>
<br><font size=1 face="sans-serif"> Pour
: rupp@mcs.anl.gov, thomas.de-soza@edf.fr</font>
<br><font size=1 face="sans-serif"> cc
: petsc-users@mcs.anl.gov</font>
<br><font size=1 face="sans-serif"> Objet
: Re: [petsc-users] Unreproducible number
of iterations for consecutives solves (GCR + ML)</font></table>
<br>
<br>
<br><font size=2 face="sans-serif"><br>
<br>
NOTE : La(les) pièce(s) jointe(s) a(ont) été supprimée(s) du message initial.
Le nom est conservé pour information.<br>
Le : 27/06/2013, à 18:18<br>
Par : Thomas DE-SOZA<br>
Nom(s) du(des) fichiers(s) : <br>
</font><font size=2 color=blue face="sans-serif"><b>C.DTF<br>
</b></font>
<br>
<br><tt><font size=2>Karl Rupp <rupp@mcs.anl.gov> writes:<br>
</font></tt>
<br><tt><font size=2>> Thus, it seems that there is a little share of
randomness involved,<br>
> which may only be significant when the solver needs to run a large<br>
> number of iterations. So, the fluctuation of iterations when using
ML<br>
> does not seem to be something you need to be worried about.<br>
</font></tt>
<br><tt><font size=2>Yes, ML has some randomness. It sets a deterministic
seed so the first<br>
solve is reproducible, but multiple solves will vary some:<br>
</font></tt>
<br><tt><font size=2>diff --git i/src/ksp/ksp/examples/tutorials/ex56.c
w/src/ksp/ksp/examples/tutorials/ex56.c<br>
index 91fad9d..fa8860c 100644<br>
--- i/src/ksp/ksp/examples/tutorials/ex56.c<br>
+++ w/src/ksp/ksp/examples/tutorials/ex56.c<br>
@@ -284,7 +284,7 @@ int main(int argc,char **args)</font></tt>
<br><tt><font size=2>PetscReal emax, emin;<br>
ierr = MaybeLogStagePush(stage[2]);CHKERRQ(ierr);<br>
/* PC setup basically */</font></tt>
<br><tt><font size=2>- ierr = MatScale(Amat, 100000.0);CHKERRQ(ierr);<br>
+ //ierr = MatScale(Amat, 100000.0);CHKERRQ(ierr);</font></tt>
<br><tt><font size=2>ierr = KSPSetOperators(ksp, Amat, Amat, SAME_NONZERO_PATTERN);CHKERRQ(ierr);<br>
ierr = KSPSetUp(ksp);CHKERRQ(ierr);</font></tt>
<br>
<br><tt><font size=2>@@ -297,7 +297,7 @@ int main(int argc,char **args)<br>
ierr = MaybeLogStagePush(stage[4]);CHKERRQ(ierr);</font></tt>
<br>
<br><tt><font size=2>/* 3rd solve */<br>
- ierr = MatScale(Amat, 100000.0);CHKERRQ(ierr);<br>
+ //ierr = MatScale(Amat, 100000.0);CHKERRQ(ierr);</font></tt>
<br><tt><font size=2>ierr = KSPSetOperators(ksp, Amat, Amat, SAME_NONZERO_PATTERN);CHKERRQ(ierr);<br>
ierr = KSPSetUp(ksp);CHKERRQ(ierr);</font></tt>
<br>
<br><tt><font size=2>$ mpiexec -n 8 ./ex56 -ne 19 -alpha 1.e-3 -ksp_monitor
-ksp_type cg -ksp_max_it 50 -pc_type ml -ksp_converged_reason -mg_levels_ksp_type
chebyshev -mg_levels_ksp_chebyshev_estimate_eigenvalues 0,0.05,0,1.05 -mg_levels_pc_type
jacobi -two_solves -ksp_norm_type unpreconditioned<br>
0 KSP Residual norm 3.916254888964e+00<br>
1 KSP Residual norm 2.881812838115e+01<br>
2 KSP Residual norm 1.275966743250e+01<br>
3 KSP Residual norm 4.773599170045e+00<br>
4 KSP Residual norm 1.935268484585e+00<br>
5 KSP Residual norm 4.209580628708e-01<br>
6 KSP Residual norm 8.134351555855e-02<br>
7 KSP Residual norm 2.105221695641e-02<br>
8 KSP Residual norm 6.251570402725e-03<br>
9 KSP Residual norm 1.693062086081e-03</font></tt>
<br><tt><font size=2>10 KSP Residual norm 4.088111376292e-04<br>
11 KSP Residual norm 8.282470497154e-05<br>
12 KSP Residual norm 2.910468516666e-05</font></tt>
<br><tt><font size=2>Linear solve converged due to CONVERGED_RTOL iterations
12<br>
0 KSP Residual norm 3.916254888964e+00<br>
1 KSP Residual norm 2.884447434423e+01<br>
2 KSP Residual norm 1.279637972963e+01<br>
3 KSP Residual norm 4.778606784425e+00<br>
4 KSP Residual norm 1.945306501447e+00<br>
5 KSP Residual norm 4.252458287438e-01<br>
6 KSP Residual norm 8.200469618341e-02<br>
7 KSP Residual norm 2.128564125382e-02<br>
8 KSP Residual norm 6.325422255484e-03<br>
9 KSP Residual norm 1.722774707230e-03</font></tt>
<br><tt><font size=2>10 KSP Residual norm 4.155306725796e-04<br>
11 KSP Residual norm 8.432468795266e-05<br>
12 KSP Residual norm 2.965043662043e-05</font></tt>
<br><tt><font size=2>Linear solve converged due to CONVERGED_RTOL iterations
12<br>
0 KSP Residual norm 3.916254888964e+00<br>
1 KSP Residual norm 2.884581541125e+01<br>
2 KSP Residual norm 1.281469034767e+01<br>
3 KSP Residual norm 4.787719947229e+00<br>
4 KSP Residual norm 1.954021039200e+00<br>
5 KSP Residual norm 4.286214813381e-01<br>
6 KSP Residual norm 8.267288000027e-02<br>
7 KSP Residual norm 2.150072898753e-02<br>
8 KSP Residual norm 6.392547836067e-03<br>
9 KSP Residual norm 1.749098960784e-03</font></tt>
<br><tt><font size=2>10 KSP Residual norm 4.214004987050e-04<br>
11 KSP Residual norm 8.561869518870e-05<br>
12 KSP Residual norm 3.013123608130e-05</font></tt>
<br><tt><font size=2>Linear solve converged due to CONVERGED_RTOL iterations
12<br>
[0]main |b-Ax|/|b|=7.693890e-06, |b|=3.916255e+00, emax=9.962246e-01</font></tt>
<br>
<br><p></p>
<p><br>
Ce message et toutes les pièces jointes (ci-après le 'Message') sont établis à l'intention exclusive des destinataires et les informations qui y figurent sont strictement confidentielles. Toute utilisation de ce Message non conforme à sa destination, toute diffusion ou toute publication totale ou partielle, est interdite sauf autorisation expresse.</p>
<p>Si vous n'êtes pas le destinataire de ce Message, il vous est interdit de le copier, de le faire suivre, de le divulguer ou d'en utiliser tout ou partie. Si vous avez reçu ce Message par erreur, merci de le supprimer de votre système, ainsi que toutes ses copies, et de n'en garder aucune trace sur quelque support que ce soit. Nous vous remercions également d'en avertir immédiatement l'expéditeur par retour du message.</p>
<p>Il est impossible de garantir que les communications par messagerie électronique arrivent en temps utile, sont sécurisées ou dénuées de toute erreur ou virus.<br>
____________________________________________________</p>
<p>This message and any attachments (the 'Message') are intended solely for the addressees. The information contained in this Message is confidential. Any use of information contained in this Message not in accord with its purpose, any dissemination or disclosure, either whole or partial, is prohibited except formal approval.</p>
<p>If you are not the addressee, you may not copy, forward, disclose or use any part of it. If you have received this message in error, please delete it and all copies from your system and notify the sender immediately by return message.</p>
<p>E-mail communication cannot be guaranteed to be timely secure, error or virus-free.</p>