MATLAB Custom Functions

MATLAB provides a powerful library of functions for user invocation, but also supports user-defined functions. This article uses an example from Vanderbilt University Professor Akos Ledeczi to explain how to customize functions in MATLAB in a step-by-step way.

First, enter the edit command in the command window to begin editing the function. The function is to randomly generate a matrix of 3 rows and 4 columns, and the elements of the matrix are in the range of 0-1.

function Myranda = rand (3,4) end

where function and end are keywords, function means that the file is a function, and end represents the end of the body of the function. Executing the myrand command in the command window results in the following:

>> Myranda =    0.5688    0.3371    0.3112    0.6020    0.4694    0.1622 0.5285 0.2630    0.0119    0.7943    0.1656    0.6541

Then, add parameters to the function. The function is to randomly generate a matrix of 3 rows and 4 columns, and the elements of the matrix are in the range of Low-high.

function A = Myrand (low, high) A = Low+rand (3,4) * (high-low); end

where low and high are the two input parameters of the function body, which represent the upper and lower bounds of the value range of the matrix element respectively; A is the range value of the function. Executing the myrand command in the command window results in the following:

>> Myrand (1,6) ans =    4.4461    1.4191    1.7619    5.9807    4.7408    2.1449    5.1291    1.3909    3.2527    5.5667    3.6917    3.2134

Finally, add a return parameter to the function. The function adds each element of a randomly generated matrix and returns its sum.

function [A, S] = Myrand (low, high) A = low + rand (3,4) * (high-low), V = a (:); s = sum (v); end

where S is the newly added return parameter. Executing the myrand command in the command window results in the following:

>> [x SS] = Myrand (2,4) x =    3.1504    2.7063    2.0860    3.4634    2.1196    3.6424    2.3380    3.2955    2.4696    2.0308    3.2982    2.9018ss =   33.5021

So far, the simple way to customize functions in MATLAB has been introduced. MATLAB also supports common looping and judging structures such as for-loop and If-else, see subsequent blogs.

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

MATLAB Custom Functions