Linear Regression

Dear Team,
I want to create strategy using Linear Regression functions. But not able to find more details about it. The link provided in documentation i.e. - is not working.
Anyone using any of the Linear Regression methods (Slope, Angle, Intercept)??
Also, want to know, how is slope / angle calculated? It’ll be really helpful if explained neatly using charts.
Thanking you well in advance for any such help in this direction.
Thanks & Regards,
Bhavesh Savla

@Nelson please try to help on this regard.
Thanks in advance