On May 31, 2012, at 11:42 AM, Matej Svejda wrote: >> As I asked on May 21, 2012, at 11:08 AM: >> >>> It is difficult to be sure, but the green curve (Mathematica solution?) >>> seems to have a small slope at alpha=1, where as the blue curve (FiPy >>> solution?) looks like it has zero slope. Could there be a difference in the >>> boundary conditions? FiPy assumes zero flux on all boundaries unless >>> specified otherwise. >> Are you sure you are solving both problems with the same boundary >> conditions? The discrepancies you are seeing are not generally >> characteristic of poor solution (whether due to excessive timesteps, grid >> resolution, or inadequate sweeping for non-linearity). Your solution is >> smooth and basically looks "OK", it just doesn't agree numerically. Poor >> solutions tend not to look right at all. > > > I didn't explain what the graph showed very well. It wasn't the solution for > a given time (which represents a probability distrubution) but rather how the > probability folded with a weighting function (which yields a scalar) changes > over time. So the graph I showed wasn't the solution calculated by FiPy. Now > I've uploaded a graph with the reference probability distribution (green) and > the calculated probability (blue) for a given time (after aprox. 300 > timesteps): http://imgur.com/6EOuk
OK. My comments still stand. The discrepancies do not have the appearance of a "bad" solution, but rather that they are not solutions to the same equation and/or boundary conditions. Are you solving the same equation and boundary conditions? How do you know? _______________________________________________ fipy mailing list [email protected] http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
