Discussion Forum

Hi all,
I am trying to solve a 2D Fokker Planck equation using Coefficient form PDE for u(x,y,t).
The initial condtion for the probability distribution u(x,y,t=0)= exp(-(x^2+y^2)/(2*0.001^2))/(2*pi*0.001^2).
which is a Narrow Gaussian distribution in x and y.
when I created this function using analytic function called Gaussxy(x,y)= exp(-(x^2+y^2)/(2*0.001^2))/(2*pi*0.001^2)
and plotted the surface plot for u(x,y) from x={-0.01, 0.01} and y={-0.01, 0.01}, the surface plot is totally wrong.
I have also tried using Gaussian pulse from analytic finction like
Gaussxy(x,y)= gp1(x)*gp1(y) which is a multiplication of two Gaussian pulses with standard deviation of 0.001.
The surface plot of this also give wrong results. I am not sure where I am making the mistake.
However, when I plotted the Indiavidual functions such as
ux(x)= exp(-(x^2)/(2*0.001^2))/sqrt(2*pi*0.001^2) gives a good Gaussian plot in x.
This is true for y also
uy(y)= exp(-(y^2)/(2*0.001^2))/sqrt(2*pi*0.001^2) gives a good Gaussian plot in y.
However, when I multiply them and plot them for x={-0.01, 0.01} and y={-0.01, 0.01}, the surface plot is totally wrong.

is there any other way that I can specify a narrow gaussian in x and y or a dirac delta function in x and y as my initial condition?
I have attached the .mph file with this..