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
