## 10 Reputation

7 years, 166 days

## 2D numerical Integration Error...

Hi,

I have been trying to solve 2D Diffusion Equation with zero Neumann BC over the unit disk. If I use Gaussian type function with a sharp peak as initial condition, I get huge errors between initial values. Let's say u(r,phi,t) is the solution of the PDE and f(r,phi) is initial value function. The expectation is for the point (r*,phi*) ,  u(r*,phi*,0)=f(r*,phi*), but it is not.

Is Numerical integration in Maple not able to handle such sharp peak? I tried some of the built-in methods such as MonteCarlo,CubaVegas but no difference.

It might be a good idea to specify some nodes arround the peak. There is a command called "peaks", but I could not use it, error message says "invalid arguments".

## Analytical solution of 2D diffusion equa...

Hello,

I have been trying to compute the analytical solution of two dimensional diffusion equation with zero neumann boundary conditions (no-flux) in polar coordinates using the solution in Andrei Polyanin's book. When I use 2d Gaussian function as initial condition, i cannot get the result. If I use some nicer function like f(r,phi)=1-r; there is no problem.

Any idea why this happens? or any suggestion to compute the analytical solution?

Thanks!

HB

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## Extracting data from a 2D plot to compar...

Maple

Hello;

I would like to extract data from a 2D plot to compare my numerical result in Matlab.

I used this command.

However, I need to spesify the nodes on x axis to get the error in Matlab. My matlab codes give the result as fix step size i.e [0 0.1 0.2 ... 1.0] or [0 0.01 0.02 ... 1.00] etc.

Is there any command in Maple to spesify the nodes on x axis?

Thanks you!

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