Section: Random Number Generation
y = randnbin(r,p)
where r is a vector of integers representing the number of
successes, and p is the probability of success.
x that occur in x+r bernoulli trials, with a success on the 
x+r trial.  The pdf is given by
 
--> randnbin(3*ones(1,4),.01) ans = 150 274 304 159 --> randnbin(6*ones(1,4),.01) ans = 657 626 357 663