On 7/6/06, <b class="gmail_sendername">Matt Funk</b> <<a href="mailto:mafunk@nmsu.edu">mafunk@nmsu.edu</a>> wrote:<div><span class="gmail_quote"></span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi,<br><br>In the html web manual for PETSc:<br><br>KSPCG is described as the preconditioned conjugate gradient iterative method<br>with: The PCG method requires both the matrix and preconditioner to be<br>symmetric positive (semi) definite.
<br><br>For KSPCG do you need to specify a preconditioner type ie: Jacobi or is there<br>a default the KSPCG uses.</blockquote><div><br>
The default on 1 proc is ILU, and many is Block Jacobi. <br>
</div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Reason for question is that for the system I am solving I need to specify<br>-pc_type none for KSPCG to run. If I do not turn the PC off then the solver
<br>does not run. Other KSP types like BiCG and GMRES work fine when I specify a<br>PC.</blockquote><div><br>
I have no idea what "deos not run" means. CG should work with any preconditioner<br>
that applies an SPD matrix.<br>
<br>
Matt<br>
</div><br></div>-- <br>"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec Guiness