[petsc-users] Convergence Criteria?

[Barry Smith]

On Sep 19, 2011, at 6:25 PM, Alan Wei wrote:

> Dear folks,
>     I hope you guys are having a nice day. 
>     I'm reading the /src/ksp/ksp/examples/tutorials/ex29.c.html and wonder how to set up the convergence criteria?

   -ksp_rtol 1.e-10 for example

   Run with -ksp_monitor_true_residual -ksp_converged_reason


> Currently I use it as a poisson solver to solve a Poisson Equation with three direction Neumann BC's and one direction Diriechlet BC's. It seems very bad on it.

    Hmm, multigrid should likely converge well. Are you sure you've set the BC's correctly?

   Barry

> 
> thanks in advance, 
> Alan