Evaluation will go back to the definition. In case of the evaluation of Functions(X,Y) it will go back to
and I guess you can imagine what happens if you call the function with x=0 (one of the values in your vector X) and if beta is greater than alpha (which will be the case with the nested loops you defined) --> division by zero (or as Prime states "a magnitude greater 10^307").
Workaround is a redefinition with a symbolic evaluation:
But there is another fault, too: you have to vectorize the function call, as otherwise expression like x*y will be taken as the vector product of X and Y and give a scalar.
