use matlab to solve this, thank you

5.2 (*). How to solve a triangular system. 1. Write a function whose heading is function x=ForwSub(A,b) computing by forward substitution (Algorithm 5.1) the solution, if it exists, of the system Ax = b, where A is a lower triangular square matrix. 2. Write similarly a function BackSub(A,b) computing the solution of a sys- tem whose matrix is upper triangular