pi_method1

代码说明：

  Estimated number of Pi ( Method 1) how do we estimate Pi by simulation? In the simulation, you keep throwing darts at random onto the dartboard. All of the darts fall within the square, but not all of them fall within the circle. Here s the key. If you throw darts completely at random, this experiment estimate the ratio of the area of the circle to the area of the square, by counting the number of darts in each. Our study of the geometry tells us this ratio is Pi/4. So, now we can estimate Pi as