MATLAB

The factorial n! of a positive number (integer) is defined by n! = n * (n-1) * (n-2)*...* 3* 2 * 1, where 0! = 1. Write a user-defined function that calculates the factorial n! of a number. For function name and arguments, use y = fact(x), where the input argument x is the number whose factorial is to be calculated and the output argument y is the value x!. The function displays an error message if a negative or non- integer number is entered when the function is called. Do NOT use MATLAB built-in function factorial. Use fact with the following numbers:

a) 9!

b) 8.5!

c) 0!

d) -5!