MATLAB Programming

3 Basic Program Components
MATLAB Functions
Many of the functions provided with MATLAB are implemented as M-files
just like the M-files that you will create with MATLAB. Other MATLAB
functions are precompiled executable programs called built-ins that run much
more efficiently.
This section discusses both types of functions and also functions that are
overloaded to handle different data types appropriately:
• “M-File Functions” on page 3-110
• “Built-In Functions” on page 3-111
• “Overloaded MATLAB Functions” on page 3-112
M-File Functions
If you look in the subdirectories of the toolbox\matlab directory, you can find
theM-filesourcestomanyofthefunctionssuppliedwithMATLAB.Youcan
locate your toolbox\matlab directory by typing
dir([matlabroot '\toolbox\matlab\'])
MATLAB functions with an M-file source are just like any other functions
coded with MATLAB. When one of these M-file functions is called, MATLAB
parses and executes each line of code in the M-file. It saves the parsed version
of the function in memory, eliminating parsing time on any further calls to
this function.
Identifying M-File Functions
To find out if a function is implementedwithanM-file,usetheexist function.
The exist function searches for the name you enter on the MATLAB path and
returns a number identifying the source. If the source is an M-file, then exist
returns the number 2. This example identifies the source for the repmat
function as an M-file:
exist repmat
ans =
2
3-110