Could you provide the codes? It would be interesting... Jan
On Tue, 12 Aug 2014 19:59:45 -0400 Aniruddha Jana <[email protected]> wrote: > Thanks for the detailed thoughts, that helps. For the time stepping, > I used the same time stepping for FiPy as given in the Fenics C-H > demo (a constant increment). I made the two codes as similar as > possible from the front end before the comparison. > > > On Aug 12, 2014, at 3:30 PM, Mike Welland <[email protected]> > wrote: > > > One contributing factor could be the difference between finite > > element vs. finite volume. In the fenics CH demo, the 4th order > > diff eq is split into 2nd order eqs. for reasons discussed under > > section 5.1.1. Mixed Form on the doc page. FiPy's demo doesn't > > seem to do that (at least as far as I can see). Finite difference > > codes also don't need to split. > > > > Now if that could explain a factor of almost 40 is another matter > > entirely. You would have to dig into things like time stepping, > > error control, etc. .e.g: It looks like FiPy uses an exponential > > time step whereas the fenics version uses a constant. > > > > Depending on what you want to do ultimately, bear in mind issues > > like parallelization, mesh refinement, supported linear backend > > (fenics = PETSc, dunno about FiPy) etc. > > > > Mike > > > > > > On Tue, Aug 12, 2014 at 2:13 PM, Aniruddha Jana <[email protected]> > > wrote: I ran with same mesh sizes and for equal time steps. > > > > On August 12, 2014 1:57:30 PM EDT, Jan Blechta > > <[email protected]> wrote: If FyPi Canh-Hilliard example > > is this one > > http://www.ctcms.nist.gov/fipy/examples/cahnHilliard/generated/examples.cahnHilliard.mesh2DCoupled.html > > > > > > then the reason is very simple: > > > > # FEniCS > > mesh = UnitSquareMesh(96, 96) > > > > # FiPy > > __name__ == "__main__": > > nx = ny = 20 > > else: > > nx = ny = 10 > > mesh = Grid2D(nx=nx, ny=ny, dx=0.25, dy=0.25) > > > > > > > > Also the function space may be different if FiPy's 'CellVariable' is > > something-like piece-wise constants. > > > > Jan > > > > > > On Tue, 12 Aug 2014 10:42:50 -0400 > > Aniruddha Jana <[email protected]> wrote: > > > > > > > > Hello, > > > > I am trying to learn FEniCS, and have been using FiPy so far. I ! > > ran > > > > the Python Cahn-Hilliard example. The program took around 80 > > seconds to run in serial, while a FiPy Cahn-Hillard program with > > similar size and settings took only 2.72 seconds. I think I am > > making some mistake > > > > > > here as I expected FEniCS to be better than FiPy in terms of > > speed. > > Can somebody please comment on the speed and memory issues, > > especially in comparison to FiPy? Since I am trying to learn using > > FEniCS, I would appreciate any such comments. > > > > > > > > Many thanks, > > Aniruddha > > > > fenics mailing list > > [email protected] > > http://fenicsproject.org/mailman/listinfo/fenics > > > > > > > > > > _______________________________________________ > > fenics mailing list > > [email protected] > > http://fenicsproject.org/mailman/listinfo/fenics > > > > > _______________________________________________ fenics mailing list [email protected] http://fenicsproject.org/mailman/listinfo/fenics
