How to roslaunch a .launch file from MATLAB and how to terminate/stop the same

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I have a launch file named freenect.launch in my workspace. The complete path to the launch file is "/home/melvin/catkin_ws/src/freenect_stack/freenect_launch". This launch file is to launch the Kinect 360 camera. I need to launch this file from the MATLAB. Once the file is launched, I need to perform some operations in the depth image of the kinect camera. After that I need to terminate/stop the freenect.launch file from MATLAB itself.

I have executed the command "echo $LD_LIBRARY_PATH" and got the response "/opt/ros/indigo/lib:/opt/ros/indigo/lib/x86_64-linux-gnu". I am not sure what to do further. Thanks in advance