Whenever a program is being written to work with a data, and the data is not yet available, it is frequently useful to test the program first by initializing the data variables to random numbers. There are various built-in functions in the MATLAB which generate random numbers.
The Random number functions or generators are not truly random. Fundamentally, the way it works is that the process begins with one number, known as a seed. Often, the initial seed is either a predetermined value or it is obtained from the built-in clock in the computer. Then, depending on this seed, a process determines the next random number. By Using that number as the seed the next time, the other random number is formed, and so forth. These are actually termed as pseudo-random; they are not truly random as there is a process which determines the next value each time.