I don't have any formulas, but my approach to the same question is put the speakers wherever they sound best for music and use the processors adjustments to get movies dialed in from there.
I got some great info. to basically the same question in my last "thread": OPTIMUM SPEAKER PLACEMENT just last week. Take a look, there are several sites suggested. Ken
You must have a verified phone number and physical address in order to post in the Audiogon Forums. Please return to Audiogon.com and complete this step. If you have any questions please contact Support.