A Physicist’s Guide to Functions in Python

Maybe you are a physicist and maybe you want to use python. Well, then this is for you. OK, let’s just jump right in.

Introduction to Functions

What is a function in python? Honestly, it’s a lot like a mathematical function. So, let’s just start with a function (totally just making up something here).

This basically like a box that you feed a number into and it spits out some other number. But I assume you already know about mathematical functions. You want to know about python functions.

Well, here’s the surprise — at a certain level, a python function is the same as a math function. OK, let’s just jump into python. Technically, I’m going to be using Glowscript. This is an online version of python with some extra stuff added (like vectors, graphing, and 3D visualizations). Trust me, it’s great.

So, let’s make a python function that does the same thing as this mathematical function. Here is the code and then I will make some comments (also, the code is online too so you can edit it and stuff).

Here is the output when you run it.

Now for some comments.

• Line 1 is just there to make this a GlowScript program — this is not a normal python thing. Don’t change this.
• Line 3 defines the function. You need to start with def and then give it a unique name (you can’t use a reserved name like sqrt since that’s already used) — but just plain “f” will work. Next you need to tell the function what variables (and how many) you are going to send to it. Finally, you need to end that first line with a colon. Everything that follows and is tab-indented is part of the function.
• Inside the function, you can make more variables. You don’t have to do it like this, but I like to create a temporary variable (is it surprising that I called it temp?).
• Line 4 takes the variable x and just performs the mathematical function. Notice that “squared” in python is **, not ^.
• Line 5 ends the function. Using return tells the function what…