Let x_{i} be a member of X patterns.
 Find distance between all pairs of patterns in X.
 Suppose the smallest distance is between pattern x_{i} and x_{j}, then replace
them by Ci, equal to the average of x_{i} and x_{j}.
 Go back to step1.
 If the smallest distance is between x_{k} and C_{j} then replace by C_{k},
or if the smallest distance is betwen C_{i} and C_{j}, then replace by a new
C.
 Go back to step 3, until no more x_{i}.
