below is the link for the code:

http://faculty.washington.edu/rjl/fdmbook/matlab/poisson.m

Write a MATLAB function poisson.m for the Poisson equation Delta u(x,y) = u(x,y) on a square m Times m grid with Delta x = Delta y = h, using the 5-point Laplacian. (a) Test your solver with the exact solution is u(x,y) = exp(x + y/2), using Dirichlet boundary conditions and the right hand side f(x,y) = 5/4 exp(x + y/2). (b) Test this script by performing a grid refinement study to verify that it is second order accurate. (c) Modify the function so that it works on a rectangular domain [a_x,b_x] Times [a_y, b_y], but still with Delta x = Delta y = h. Test your modified script on a non-square domain. (d) Further modify the code to allow Delta x Delta y and test the modified script. Write a MATLAB function poisson.m for the Poisson equation Delta u(x,y) = u(x,y) on a square m Times m grid with Delta x = Delta y = h, using the 5-point Laplacian. (a) Test your solver with the exact solution is u(x,y) = exp(x + y/2), using Dirichlet boundary conditions and the right hand side f(x,y) = 5/4 exp(x + y/2). (b) Test this script by performing a grid refinement study to verify that it is second order accurate. (c) Modify the function so that it works on a rectangular domain [a_x,b_x] Times [a_y, b_y], but still with Delta x = Delta y = h. Test your modified script on a non-square domain. (d) Further modify the code to allow Delta x Delta y and test the modified script