On Mon, Dec 7, 2009 at 4:56 AM, John-Oliver Engler <
[email protected]> wrote:

>
> Hi there,
>
> I am currently trying to set the initial conditions of a one dimensional
> Fokker-Planck equation. I want to have sth like p(x_0,t=0) = 10, p(x \neq
> x_0, t=0) = 0. However, if I type the following code
>
> from fipy import *
> from numpy import *
> from pylab import *
>
> """ Building a 1d linear grid with nx evaluation points that are equally
> spaced
>    with interval dx """
>
> nx = 500
> dx = -0.01


Since dx <0, every CellCenter on the mesh is nonpositive.


>

mesh = Grid1D(nx=nx, dx=dx)
>
> m = 1.5
> D = 0.5
>
> """ Initial Conditions """
>
> y0 = 0.0
> pos = CellVariable(name = '$p(y)$', mesh = mesh, value = y0)
>
> y = mesh.getCellCenters()#[...,0]
>
> pos.setValue(10.0, where =(4.0<y) & (y<4.1))
>

Since every CellCenter is nonpositive, no CellCenter is larger than 4. This
is why the value is zero everywhere.


> viewer=Viewer(vars=pos)
> viewer.plot
>
> I only see a horizontal line so that p(y) = 0. FiPy seems to ignore my
> setValue command. Or do I miss something?
>
> Thanks,
>
> Oliver
>
>
>
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