MATLAB Programming

3 Basic Program Components
Forcing a Built-In Call
If you overload any of the MATLAB built-in functions to handle a specific data
type, then MATLAB will always call the overloaded function on that type. If,
for some reason, you need to call the built-in version, you can override the
usual calling mechanism using a function called builtin. The expression
builtin('reshape', arg1, arg2, ..., argN);
forces a call to MATLAB built-in reshape, passing the arguments shown even
though an overload exists for the data types in this argument list.
Overloaded MATLAB Functions
An overloaded function is an additional implementation of an existing
function that has been designed specifically to handle a certain data type.
Whenyoupassanargumentofthistypeinacalltothefunction,MATLAB
looks for the function implementation that handles that type and executes
that function code.
Each overloaded MATLAB function has an M-file on the MATLAB path. The
M-files for a certain data type (or class) are placed in a directory named with
an @ sign followed by the class name. For example, to overload the MATLAB
plot function to plot expressions of a class named polynom differently than
other data types, you would create a directory called @polynom and store your
own version of plot.m in that directory.
You can add your own overloads to any function by creating a class directory
for the data type you wish to support for that function, and creating an M-file
that handles that type in a manner different from the default. See “Setting
Up Class Directories” on page 9-6 and “Designing User Classes in MATLAB”
on page 9-9.
When you use the which command with the -all option, MATLAB returns
all occurrences of the file you are looking for. This is an easy way to find
functions that are overloaded:
which -all set
% Show all implementations for 'set'
3-112