Barry, thank you very much for the suggestion and the clarification.<br><br>Yan<br><br><br>PS: It should be -ksp_right_pc, instead of -ksp_pc_right:<br><br>-ksp_monitor_draw_true_residual: Monitor graphically true residual norm (KSPMonitorSet)<br>
-ksp_monitor_range_draw: Monitor graphically preconditioned residual norm (KSPMonitorSet)<br> Pick at most one of -------------<br> -ksp_left_pc: Use left preconditioning (KSPSetPreconditionerSide)<br> -ksp_right_pc: Use right preconditioning (KSPSetPreconditionerSide)<br>
-ksp_symmetric_pc: Use symmetric (factorized) preconditioning (KSPSetPreconditionerSide)<br> -ksp_compute_singularvalues: Compute singular values of preconditioned operator (KSPSetComputeSingularValues)<br> -ksp_compute_eigenvalues: Compute eigenvalues of preconditioned operator (KSPSetComputeSingularValues)<br>
<br><br><br><br><div class="gmail_quote">On Tue, Jul 28, 2009 at 9:28 PM, Barry Smith <span dir="ltr"><<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
This depends on the Krylov solver and if you are using left or right preconditioning. With right preconditioning it always uses the true residual norm.<br>
So you can do -ksp_type gmres -ksp_pc_right<br>
Some methods we do not have implemented for right preconditioning, like CG, in that case you can use -ksp_type cg -ksp_norm_type unpreconditioned<br>
For CG many people prefer the energy norm which you can access with -ksp_norm_type natural<br>
<br>
-ksp_view should always show which it is using<br><font color="#888888">
<br>
Barry</font><div><div></div><div class="h5"><br>
<br>
On Jul 28, 2009, at 8:15 PM, Ryan Yan wrote:<br>
<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi all,<br>
Is there any way to set a true residual tolerance on command line. -ksp_atol is for preconditioned residual norm only.<br>
<br>
Thanks,<br>
<br>
Yan<br>
</blockquote>
<br>
</div></div></blockquote></div><br>