Section 2: Introduction to IDL functions and procedures

We've done some simple maths and a simple plot (putting the IDL code in a file and using the command line), but this isn't a very powerful way of programming. One key to good programming is to put each component operation in a separate file, and you can then reuse that file many times. We have created a program already, which we ran using ``.run'', but by using ``functions'' and ``procedures'' you can pass things into the code in the file, which then passes the answers back out - this is very useful.