Is there a was for Flash to calculate the general trend of a collection of dots?

from: http://forum.java.sun.com/thread.jsp...sageID=3889578
"You would have point objects which will be holding (x, y) coordinates. From then on, it's just simple S1 stats. Your line is given by the equation y = mx + b where m is the gradient and b is the interception with the y-axis. You can calculate m using m = ( n*(E(xy)) - (Ex)*(Ey) ) / ( (n*(E(x^2)) - (Ex)^2) ) and b using b = ( E(y) - m*(E(x)) ) / n where n is the number of point objects and x and y are the respective coordinates(E stands for the sum of)."

I got lost at what E stands for, could anyone please explain.