How to define a constrained region in 2D for a function?

Hi everyone,

I am trying to find the minimum point of the function by using steepest descent algorithm. When the code stars running, derivatives and variables go to infinity. So, I want to put a constrained region on which my objective function works as it is searching the minimum without exceeding this defined region as a constraint. I think this may work.

The problem is that I do not know how I can add a constrained region on which the code works without exceeding that defined region.

I beg to your immediate help. Thanks