dx needs to be a float: `dx = 1.` This doesn't always seem to be true, but it is often enough that we should figure out how to fix it or raise an error.
https://github.com/usnistgov/fipy/issues/672 > On Sep 26, 2019, at 7:29 PM, Justin Pothoof <jpoth...@uw.edu> wrote: > > Hello, > > I'm trying to set up a 2D diffusion problem. I noticed that if i > print(shape(CellVariable.value)) after defining a CellVariable I get the > output (2000,) for example.. which isn't a 2D array. I decided to test the > 2D diffusion example provided, but I encounter the "RuntimeError: Factor is > exactly singular" and it also will not plot. It is copied straight from the > mesh.20x20 example, so I'm not sure why it will not run. > > from fipy import CellVariable, Grid2D, Viewer, TransientTerm, DiffusionTerm > from fipy.tools import numerix > > nx = 20 > ny = nx > dx = 1 > dy = dx > L = dx * nx > mesh = Grid2D(dx=dx, dy=dy, nx=nx, ny=ny) > > phi = CellVariable(name="solution variable", mesh=mesh, value=0.) > D = 1 > eq = TransientTerm() == DiffusionTerm(coeff=D) > > valueTopLeft = 0 > valueBottomRight = 1 > > X, Y = mesh.faceCenters > facesTopLeft = ((mesh.facesLeft & (Y > L / 2)) | (mesh.facesTop & (X < L / > 2))) > facesBottomRight = ((mesh.facesRight & (Y < L / 2)) | (mesh.facesBottom & (X > > L / 2))) > > phi.constrain(valueTopLeft, facesTopLeft) > phi.constrain(valueBottomRight, facesBottomRight) > > > if __name__ == '__main__': > viewer = Viewer(vars=phi, datamin=0., datamax=1.) > viewer.plot() > > timeStepDuration = 10 * 0.9 * dx**2 / (2 * D) > steps = 10 > for step in range(steps): > eq.solve(var=phi, dt=timeStepDuration) > if __name__ == '__main__': > viewer.plot() > Justin Pothoof > The University of Washington - Department of Chemistry > Pre-Candidacy PhD Student > Ginger Group > _______________________________________________ > fipy mailing list > fipy@nist.gov > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] _______________________________________________ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
