Help with Newton divided method

I'm trying a very simple code for Newton divided method, I'm exhausted, this Matlab stuff is wearing me down. I'm frustrated, I've tried all the codes in the book, but it always returns with an error of some sort. This is the latest one.

newtdd([1970,1990],[3707475887, 5281653820], 2)

"Maximum recursion limit of 500 reached. Use set(0,'RecursionLimit',N) to change the limit. Be aware that exceeding your available stack space can crash MATLAB and/or your computer."

Error in newtdd

I'm given estimated population for 1970 and 1990, all I have to do is find a code that will calculate an estimate for 1980 using those 2 estimates. They come in x and y values, the Xs are 1970 and 1990 and the Ys are the population. Easy garbage on paper, but I can't figure this Matlab thing to save my life, been on this for over a week now.

Answer 1

[Gervais]

By the way I was using Matlab R2012b before, I replaced that today with R2013b hoping the recursion limit error would go away. I don't know how to extend the limit, I've tried the set(0, recursionlimit,10000) code, NOTHING. It's so frustrating..