gawk '{
        n++; x0+=$1; y0+=$2; x[n] = $1; y[n] = $2
}END{
     
        if ( n == 0 ) {
                printf( "Error in xycorr. Number of lines %i\n", n );
                exit
        }
         
        x0 /= n;
        y0 /= n;
        for ( i=1; i<=n; i++ ) {
                t += ( x[i] - x0 ) * ( y[i] - y0 );
                nx += ( x[i] - x0 ) * ( x[i] - x0 );
                ny += ( y[i] - y0 ) * ( y[i] - y0 );
        }
         
        if ( nx * ny == 0.0 ) {
                c = 0.0        
        }
        else {
                c = t/sqrt(nx*ny);
        }
         
        printf( "Pearson coefficient for N= %i data: %8.5f\n", n, c );
}'