There's something wrong with the math. I tried the integral from 0 to 200 of e^(-x^2) and it gave me 0. It also gives me 0 for the range 0 to 1, and for using x^2 instead of -x^2.
I then tried from 0 to 2 of e^(-x) and it gave me −0.864664716763, which is negative of what it should be.