Extras: Introduction to M-files


What is an m-file?

An m-file, or script file, is a simple text file where you can place MATLAB commands. When the file is run, MATLAB reads the commands and executes them exactly as it would if you had typed each command sequentially at the MATLAB prompt. All m-file names must end with the extension '.m' (e.g. test.m). If you create a new m-file with the same name as an existing m-file, MATLAB will choose the one which appears first in the path order (type help path in the command window for more information). To make life easier, choose a name for your m-file which doesn't already exist. To see if a filename.m already exists, type help filename at the MATLAB prompt.

Why use m-files?

For simple problems, entering your requests at the MATLAB prompt is fast and efficient. However, as the number of commands increases or trial and error is done by changing certain variables or values, typing the commands over and over at the MATLAB prompt becomes tedious. M-files will be helpful and almost necessary in these cases.

How to create, save or open an m-file?

If you are using PC or Mac:

To create an m-file, choose New from the File menu and select Script. This procedure brings up a text editor window in which you can enter MATLAB commands.

To save the m-file, simply go to the File menu and choose Save (remember to save it with the '.m' extension). To open an existing m-file, go to the File menu and choose Open.

If you are using Unix:

To create an m-file, use your favorite text editor (pico, nedit, vi, emacs, etc.) to create a file with .m extension (e.g. filename.m).

How to run the m-file?

After the m-file is saved with the name filename.m in the current MATLAB folder or directory, you can execute the commands in the m-file by simply typing filename at the MATLAB command window prompt.

If you don't want to run the whole m-file, you can just copy the part of the m-file that you want to run and paste it at the MATLAB prompt.