— Function: double gsl_stats_correlation (const double data1[], const size_t stride1, const double data2[], const size_t stride2, const size_t n)

This function efficiently computes the Pearson correlation coefficient between the datasets data1 and data2 which must both be of the same length n.

          r = cov(x, y) / (\Hat\sigma_x \Hat\sigma_y)
            = {1/(n-1) \sum (x_i - \Hat x) (y_i - \Hat y)
               \over
               \sqrt{1/(n-1) \sum (x_i - \Hat x)^2} \sqrt{1/(n-1) \sum (y_i - \Hat y)^2}
              }