None of your functions do anything, as they do not return any output arguments (or use any other methods to change data, e.g. via nested functions). For example, the functions called inside Gauss function appear to do nothing, and the variables er and x never change, thus making the Gauss function's purpose rather moot.
As Steven Lord wrote, it really looks like you are writing in another language, perhaps one which uses pass-by-reference (which MATLAB does not) or something similar. You should probably do the introductory tutorials to learn basic MATLAB concepts, such as how to call functions and return arguments from them.
Writing lots and lots of code without testing or understanding what it does is a common way that beginners get stuck. You should not write your second lilne of code until your first line of code is checked and tested and does exactly what you need it to do. Only then should you move on to writing the second line. Then you will not end up with one page of code and no idea what it is doing.
Your code has quite a few mlint messages shown in the Editor, which indicate likely mistakes and bugs. For example, the er input arguments are unused. This line does nothing:
length s(n);
