A blog to help electrical engineers and students to learn electrical engineering topics. Basic Electrical Engineering, Power Systems, Electrical Machines, tec.. Now special course on MATLAB for Beginners.



Monday, December 26, 2016

User Defined Functions in MATLAB Part -2

Previous post we discussed what is a user defined function in MATLAB. This lecture we will discuss how to define a function and how to call the function in a script.

Components of a function is discussed in the previous lecture. The first statement in a function must be function definition.The basic syntax of a function definition is:

function[a, b, c]= basicmath(x,y)

Basically a function accepts an input vector, perform the operation, and returns a result. The sample function given has two input variables and three output variables. But we can also have functions without input or/and output.

Under some special occasions we may need some functions without any input or output.

Some functions will take some input arguments but will not return any output arguments. Functions to plot some shapes or curves and functions to display some message are examples.

A function can be called from the command window or inside a script or function. To run a function in command window, just type the name of comment with proper input and output arguments.

Thursday, December 1, 2016

User Defined Functions in MATLAB - Part 1

User-defined functions are similar to the MATLAB predefined functions. A function is a MATLAB program that can accept inputs and produce outputs. A function can be called or executed by another program or function. Code for a function is done in an Editor window or any text editor same way as script and saved as m-file. The m-file must have the same name as the function.

It is important that you give meaningful variable names to variables inside a function that you write, so that you and others can understand what the function does. The function M-file must be saved in your current directory.

The declaration statement 'function' is used to define the file as a function. It must be typed in lower case letters. Rules for giving function name is same as the rules for variable names.
Input arguments are typed in side the parentheses ( ). They are used to transfer data into function from calling program. Can be zero or more input arguments. 
Output arguments are typed inside the square brackets [ ]. They are used to transfer data out of function to calling program. Can be zero or more output arguments. It is important to give a meaningful variable names.