MATLAB Programming

4 M-File Programming
Simple Function Example
The average functionisasimpleM-filethatcalculatestheaverageofthe
elements in a vector:
function y = average(x)
% AVERAGE Mean of vector elements.
% AVERAGE(X), where X is a vector, is the mean of vector
% elements. Nonvector input results in an error.
[m,n] = size(x);
if (~((m == 1) | (n == 1)) | (m == 1 & n == 1))
error('Input must be a vector')
end
y = sum(x)/length(x); % Actual computation
Try entering these commands in an M-file called average.m. Theaverage
function accepts a single input argument and returns a single output
argument. To call the average function, enter
z = 1:99;
average(z)
ans =
50
Types of Functions
MATLAB provides the following types of functions. Each function type is
described in more detail in a later section of this documentation:
• The “Primary M-File Functions” on page 5-15 is the first function in an
M-file and typically contains the main program.
• “Subfunctions” on page 5-33 act as subroutines to the main function. You
can also use them to define multiple functions within a single M-file.
• “Nested Functions” on page 5-16 are functions defined within another
function. They can help to improve the readability of your program and
also give you more flexible access to variables in the M-file.
• “Anonymous Functions” on page 5-3 provide a quick way of making a
function from any MATLAB expression. You can compose anonymous
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