Ultimate Trader uses the Least-Squares Line method to determine the plot points for the Best-Fit trend line.
Formula for Least-Squares Line:
The least-squares line uses a straight line
To approximate the given set of data, (X1,Y1) , (X2,Y2)
, ..., (Xn,Yn)
, where 
.
The best fitting curve 
has the least square error, i.e.,
NOTE: a and b are unknown coefficients while all X1 and Y1 are given. To obtain the least square error, the unknown coefficients a and b must yield zero first derivatives.
Expanding the above equations, we have:
The unknown coefficients a and b can therefore be obtained:
where 
stands for 