similarity calculation pearson correlation coefficient calculation A pearson correlation coefficient calculation is a similarity calculation which attaches to each pair of random variables X and Y the ratio of their covariance by the product of their standard deviations. Given a series of n measurements of X and Y written as x_i and y_i where i = 1, 2, ..., n, then their Pearson correlation coefficient refers to the "sample correlation coefficient" and is written as the sum over i of the ratios (x_i-xbar)*(y_i-ybar)/((n-1)*s_x*s_y) where xbar and ybar are the sample means of X and Y , s_x and s_y are the sample standard deviations of X and Y. The closer the pearson correlation coefficient is to 1, the more similar the inputs are considered. Elisabetta Manduchi PERSON: Elisabetta Manduchi WEB: http://en.wikipedia.org/wiki/Correlation pearson correlation coefficient calculation ready for release