Given the $2$ variable function:

x & y should both have $50$ evenly spaced values between $-5$ & $5$

Create a matrix of values z using nested for loops

Create a surface plot of z

Create a new matrix $($New$\_$z$)$ that is identical to z except: if z$<=0,$ New$\_$z$=0.$

Create a surface plot of New$\_$z in a separate figure.

All figures should have appropriate labels and titles