On Thu, Sep 13, 2012 at 4:06 PM, David Knezevic
<[email protected]>wrote:

> On a related issue, I wanted to mention 3D linear elasticity example
> that I added: systems_of_equations_ex6. It seems very slow with the
> default iterative solver in PETSc (ILU + GMRES, right?). The example
> takes 26 seconds on my laptop.
>
> But this is a symmetric problem, so you'd expect CG to be good.


Yes, in another lifetime when I was doing nonlinear elasticity, CG was
quite good.


> Calling
> ./systems_of_equations_ex6-opt -ksp_type cg
> runs fast, but gives the wrong answer


That's alarming...

Is ICC the default preconditioner with CG? If not, give that a try (maybe
with -pc_factor_levels 4 or something)
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