If the curve lies either partly or wholly above or below Y = 0, change the Y values 

 of point coordinates from the curve to Y' = (Y - Y minimum) --for example: 



(Y) 



(X) 



(Y) 



-3 



(Y) 



(X) 



Y' 



=Y-(-5) 



Y 



Y' 



=Y-(-3) 



-3 







-1 



2 



1 



4 



Y' 



=Y-(1) 



Plotting Y' instead of Y, all three curves would appear as: 



And, last, X' and Y' would be substituted for X and Y, respectively, when looking for a 

 suitable form in the Standards. 



36 



