2D transient heat conduction in a rectangular plate

Hello i tried to solve 2d temperature profile in a rectangular plate where the initial condition is T=200 and Temperature at all 4 boundaries is set to 100.the code runs with no errors but the result is a matrice that all of its components are 200. And i think something is wrong specially about boundary conditions. Thanks for your help

Answer 1

[Torsten]

In the computation of the second-order derivatives in x and y direction, you don't use that the temperature at the boundaries is 100 instead of 200. You work with T = 200 everywhere. The setting at the end of "testpde2" doesn't help - it has no influence on delT2_x and delT2_y. You must prescribe T = 100 at the boundaries in your initial conditions !