Introduction

Welcome everyone! Today we will start learning about M-files in MATLAB. Does anyone know what an M-file is?

Is it a file that contains MATLAB code?

Exactly, Student_1! M-files are files with a '.m' extension that store sequences of MATLAB commands. They allow us to save and run commands multiple times. Why do you think it’s beneficial to use M-files?

So we don’t have to retype commands every time we want to run them?

That's right! Saving commands in M-files makes it easier to organize and reuse your code. Let’s remember that: M-files = Save + Reuse. Can anyone think of examples why we might need to reuse commands?

We might need to use the same commands for different datasets!

Great point! Let's move on to how to create an M-file. You can create one using the MATLAB editor, which is optimized for writing and debugging these files.

Now let’s talk about how to create an M-file. What steps do you think are important?

We need to open the editor and then write some commands.

Exactly! After writing our commands, we can save the file with a '.m' extension. Student_1, can you describe how you would run this M-file once it’s saved?

I can just type the name of the file in the Command Window!

Correct! For example, if we save it as 'example1.m', we would type '>> example1' in the Command Window. Does anyone remember the effect of running a script?

All variables created in the script will stay in the workspace.

Exactly, and sometimes that can lead to issues if we overwrite existing variables. We will discuss that next. Remember: Scripts save time but can create conflicts.

We've learned about creating M-files, now let’s discuss side effects. What do you think the term 'side effects' means in this context?

Does it mean something negative that happens when we run a script?

Exactly! Scripts can have side effects like overwriting existing variables in the workspace. Why might this be problematic?

If we’re using a variable in our workspace and then the script changes it, it could mess up our calculations.

Great observation! This is why for complicated applications, it’s often better to use M-file functions instead. Remember: Scripts = Easy Reuse, but watch out for Side Effects!

Let’s transition to M-file functions. Who can tell me how functions differ from scripts?

Functions can accept input arguments and return outputs, while scripts cannot.

Exactly, Student_2! Functions have their own workspace separate from the base workspace. This protects against variable conflicts. What do we call the first line of a function file?

It's the function definition line?

Yes! The function definition line indicates the name of the function and its input/output arguments. Side Note: Remember, the file name should also match the function name!

Now, how about we create a sample function together? What function could we create?

We could create a function to calculate the factorial of a number!

Great idea! Can anyone outline the steps we need to create this factorial function?

First, we need to define it and then calculate the product of numbers from 1 to n.

Exactly! Let’s remember the structure: function definition, then the body with code. And remember, functions separate their variables from the base MATLAB workspace.

So we would use 'function f = factorial(n)' and then calculate with 'f = prod(1:n);' right?

Spot on! Remember to keep practicing creating functions. Functions in MATLAB provide clarity and prevent variable conflicts.