[petsc-users] sundials vs beuler

[Jed Brown]

On Thu, 29 Jul 2010 11:32:21 -0400, Xuan YU <xxy113 at psu.edu> wrote:
> Hi
> 
> 
> I solve my problem with TS, but different type: beuler and sundials,  
> time consumption changes dramatically. (time of beuler is 1m12s, time  
> of sundials is 1.8s).

BEULER takes 4181 steps, Sundials takes very few (can't tell exactly
from -log_summary, run with -ts_view for details).  Have you checked the
accuracy of the result?

> I was told that sundials can not control the minimum time step, so the  
> performance will be slower.

The maximum time step might be more of an issue here.  CVode actually
does allow setting this, but PETSc's interface doesn't currently expose
it.  I just added it to petsc-dev so you may want to try that.

Jed