Matlab Tutorial - M Files (Scripts)

M-files are macros of MATLAB commands. The M-files are stored as ordinary text files with the extension m, filename.m. An M-file can be either a function with input and output variables or a list of commands.

Where should we put the M-files?

MATLAB requires that the M-file must be stored either in the working directory or in a directory that is specified in the MATLAB path list.

On Windows, the default location is C:\Documents and Settings\user\My Documents\MATLAB. We can check it by New->Script and then Save As:

Suppose we want to have the M-files in C:\Documents and Settings\user\My Documents\MATLAB\FFT. We can let Matlab know where it can find the file in two ways:

1. Change the working directory by issuing cd path command:

   >> pwd
   ans =
   C:\Documents and Settings\admin\My Documents\MATLAB
   >> cd FFT
   >> pwd
   ans =
   C:\Documents and Settings\admin\My Documents\MATLAB\FFT
   

2. Add the directory to the path.
   1. Permanent addition to the path : edit the ....\MATLAB\matlabrc.m file
   2. Temporary modification to the path : issue a command, path(path,'C:\Documents and Settings\user\My Documents\MATLAB\FFT') withing Matlab

In this section, we'll see how the M-files are used.

Let's create a file in our working directory (the default directory mentioned in previous section). Name it as cexp.m that has the following commands:

function fval = cexp(a,b)
fval = exp(a+b*i)

Then within the command window:

>> x = 1;
>> y = 2;
>> cexp(x,y)
fval =
  -1.1312 + 2.4717i
ans =
  -1.1312 + 2.4717i
>>