[Ar-list] DRF in Excel

[Carter T. Butts]

Matthew Selznick wrote:
> Man, I'm just full of questions!
> 
> I'm trying to create a DRF Graph in Excel, but I'm no mathematician.
> Does anyone have any experience entering the formula as an excel
> formula?
> 

Sure; it should be pretty trivial.  If, for instance, cell A1 has the 
rating you wish to convert, then

=(1/pi())*atan(A1/(10*pi()))+0.5

should do the trick.  To perform the inverse operation (rolling targets 
to ratings), use

=10*pi()*tan(pi()*A1-pi()/2)

(I just tried these in Gnumeric, and they worked fine -- they should 
function equivalently in Excel, so far as I am aware.)

Actually, if you (or others) are interested, I've got some Excel sheets 
with DRF tables I could send.  You could easily implement them yourself, 
but I'm happy to share....

-Carter