MATLAB Programming

Function Arguments
Function Arguments
When calling a function, the caller provides the function with any data it
needs by passing the data in an argument list. Data that needs to be returned
to the caller is passed back in a list of return values.
Semantically speaking, MATLAB always passes argument data by value.
(Internally, MATLAB optimizes away any unnecessary copy operations.)
If you pass data to a function that then modifies this data, you will need to
update your own copy of the data. You can do this by having the function
return the updated value as an output argument.
This section covers
• “Checking the Number of Input Arguments” on page 4-33
• “Passing Variable Numbers of Arguments” on page 4-35
• “Parsing Inputs with inputParser” on page 4-37
• “Passing Optional Arguments to Nested Functions” on page 4-48
• “Returning Modified Input Arguments” on page 4-51
Checking the Number of Input Arguments
The nargin and nargout functions enable you to determine how many input
and output arguments a function is called with. You can then use conditional
statements to perform different tasks depending on the number of arguments.
For example,
function c = testarg1(a, b)
if (nargin == 1)
c = a .^ 2;
elseif (nargin == 2)
c = a + b;
end
Given a single input argument, this function squares the input value. Given
two inputs, it adds them together.
4-33