question: public static double uncenteredCorrelation ( NumberVector x , NumberVector y ) { final int xdim = x . getDimensionality ( ) , ydim = y . getDimensionality ( ) ; if ( xdim != ydim ) { throw new IllegalArgumentException ( "Invalid arguments: number vectors differ in dimensionality." ) ; } double sumXX = 0. , sumYY = 0. , sumXY = 0. ; for ( int i = 0 ; i < xdim ; i ++ ) { final double xv = x . doubleValue ( i ) , yv = y . doubleValue ( i ) ; sumXX += xv * xv ; sumYY += yv * yv ; sumXY += xv * yv ; } if ( ! ( sumXX > 0. && sumYY > 0. ) ) { return ( sumXX == sumYY ) ? 1. : 0. ; } return sumXY / Math . sqrt ( sumXX * sumYY ) ; }
target:  Compute the uncentered correlation of two vectors.