please, how can I use underrelaxation or overrelaxation in my gauss seidel code to make it fast and why its given me the initial temperatures as the answer?

I'm trying to solve energy balance equations of a flat plate solar collector components(Glass cover, Air gap, Absorber, and Heat transfer fluid) using implicit finite difference in an iterative form but the code is very slow and its given me the initial temperature as my answer.

[Amjad Green]

can i see your code

[John D'Errico]

Gauss-Seidel is a method used to solve a linear system of equations. Why would you bother to use it in MATLAB though? Well, except in a homework assignment, which this does not seem to be?

[Gadosky571]

@Amjad Green the code is attach here.