Linear regression and correlation coefficient.   Enter x and y of the data  and  (possibly) the P
through which the graph is constrained to pass  (if you don't put anything, the centroid is taken)

P:     x separated by "," ↑   -   y separated by "," ↓      

y =  x   +  
xM   yM    ← ↑ Round according to the context!
correlation coefficient