MATLAB: Nonlinear 2D elliptic problem u_xx+u_yy= f(x,y)

2d possoin equation matrix dimensions

x is in (0,1) , y (0,1) and u =0 pn boundaries.

My problem is equivalent to this matrix formulation: (attached).

However, I am stuck on the last part of my code! If anyone can take look and tell me, how to correct it,

f=reshape(f',(Nx+1)*(Ny+1),1);

Best wishes

Torsten.

I have no idea what a ‘cloud set’ is, although creating the function (here as an anonymous funciton) is straightforward:

f = @(x,y) -(x-10).^2 -(y-10).^2;
[X,Y] = meshgrid(-10:10);
figure(1)
meshc(X, Y, f(X,Y))
grid on

See the documentation on Function Basics (link) for the details on creating and using functions.

I added the plot for fun, and to demonstrate how to call the function.

Take a look at the example "Multiple Numerical Integrations" under

Best wishes

Torsten.