Seems like the formula is simply a fine enough Riemann sum for calculating Gaussian integral int_-inf^inf e^(-x^2) dx = sqrt(pi). It makes it much less surprisi

Seems like the formula is simply a fine enough Riemann sum for calculating Gaussian integral int_-inf^inf e^(-x^2) dx = sqrt(pi). It makes it much less surprising, though the exact estimation of error is still quite ingenious and worth following.