Math, C, Calculus, Numerical Analysis, Monte Carlo.
0.0 -> 20.0 is 3.715, STD = 0.4479, (256 iterations) Estimate for 0.0 -> 20.0 is 3.591, STD = 0.2133, (1024 iterations) Estimate for 0.0 -> 20.0 is 3.388, STD = 0.1053, (4096 iterations) Estimate for 0.0 -> 20.0 is 3.579, STD = 0.0538, (16384 iterations) Stratified Sampling  Estimate for 0.0 ->