How to 'call' Matlab functions from another script

All the information provided in my answer can be found in Function Basics at MATHWORKS.

How to make a function in MATLAB? You use the following template. In addition the name of the function and the name of the file should be similar.

% ------------------- newFunc.m--------------------
function [out1,out2] = newFunc(in1,in2)
out1 = in1 + in2;
out2 = in1 - in2;
end
%--------------------------------------------------

For using multiple functions you can apply them either in separate m-files or using nested/local structures:

Separate m-files:

In this structure you put each function in a separate file and then you call them in the main file by their names:

%--------- main.m ----------------
% considering that you have written two functions calling `func1.m` and `func2.m`
[y1] = func1(x1,x2);
[y2] = func2(x1,y1);
% -------------------------------

local functions:

In this structure you have a single m-file and inside this file you can define multiple functions, such as:

% ------ main.m----------------
    function [y]=main(x)
    disp('call the local function');
    y=local1(x)
    end

    function [y1]=local1(x1)
    y1=x1*2;
    end
%---------------------------------------

Nested functions:

In this structure functions can be contained in another function, such as:

%------------------ parent.m -------------------
function parent
disp('This is the parent function')
nestedfx

   function nestedfx
      disp('This is the nested function')
   end

end
% -------------------------------------------

You cannot call nested function from outside of the m-files. To do so you have to use either separate m-files for each function, or using class structure.