Function programming task 2. Credit Card Validator 
Takes in a credit card number from a common credit card vendor (Visa, MasterCard, American Express, Discoverer) and validates it to make sure that it is a valid number  

6. write a user-defined matlab function for the following math function: r() = 4cos(4sin ) the input to the function is  (in radians) and the output is r. write the function such that  can be a vector. a) use the function to calculate r(/6) and r(5/6). b) use the function to plot (polar plot) r() for 0 ≤  ≤ 2. hint: use “ polar” and/or for “polar plot in matlab." include the title “'r(\theta)=4cos(4sin(\theta))”