It is not possible to have functions inside a script file. Functions can only go inside function files.
To read values from a file, use load() or importdata() or uiimport() or csvread() or xlsread() or dlmread() or textscan() or the basic I/O functions such as fgetl() and fscanf().
There are lot of examples around of passing variables into functions. See http://www.mathworks.com/help/techdoc/ref/function.html
