After reading the MATLAB Getting help Functions topic, you will understand how to use MATLAB help commands to take full advantages of various features available in MATLAB.
MATLAB documents are available for providing help on MATLAB topics. To view the documentation, click on the MATLAB help button 
display on the MATLAB Home menu and MATLAB help window appears shown below
MATLAB – Help Using Commands:
For explanation purpose, I will search trigonometric sine function using MATLAB help commands, describe below one by one and see the results. The trigonometric sine function defined as sin function in MATLAB.
If you want information about any command in MATLAB various help commands available are:
help command
The help command shows information about the command/function in the command window. The help command shows exact information about the search function/command name. The general form of the command is:
help command/function_name
MATLAB VIEW – to show help command execution
Let us search for sin function using help command. After executing help command for sin function on the command window result appears will look like –
lookfor command
The lookfor command shows full information about the command/function in the command window. The lookfor command shows information of each search for a match function name. The general form of the command is:
lookfor command/function_name
MATLAB VIEW – to show lookfor command execution
Let us search for sin function using lookfor command. After executing lookfor command for sin function on the command window, result display below–
In the above figure, results continuously displayed, so to stop execution press ctrl + C,
doc command
The doc command shows help manual about search command/function name. The general form of the command is:
doc command/function_name
MATLAB VIEW – to show doc command execution
Let us search for sin function using doc command. After executing doc command for sin function on the command window the result display below–
In the above figure shows once we execute doc sin command the sin doc help will popup.