1. A hardware attachment to a computer used for computing a correlation function of random sampled data comprising: first and second memories for storing two sets of said sampled data; a third memory for storing the interarrival times between adjacent samples of said sampled data; means for sequentially multiplying together all possible combinations of the random sampled data stored in said first and second memories; fourth and fifth memories; and means responsive to said multiplying means and said third memory for storing in said fourth memory the multiplications made by said multiplication means in locations corresponding to the interarrival times between the data points multiplied together and for storing in said fifth memory the number of times a multiplication is stored in said fourth memory in each of said locations corresponding to an interarrival time between data points.