Ok, I sent an Email to Gerald Perry of Perry Systems and we chatted on the phone as well.
This is the email that I sent.
Sent: Wednesday, May 14, 2008 9:06 AM
Subject: Uphill, Downhill
The Exbal program as far as I can tell doe not have a feature to indicate if the angle is uphill or downhill. The reason that I ask is that I was involved in a discussion and the affects of gravity on shooting uphill or downhill at 45 degree of angle. I took the position that it did not matter and a couple of guys claimed that gravity would effect velocity at Longer distances is this fact or not
This is the reply that I recieved from Mr. Perry
Gravity is not the issue for any minute difference between up hill and down hill shots. It is the air density differences which are pretty small unless you are shooting from an airplane. J
Gerald L. Perry
Perry-Systems - Ballistic Calculator Software
When speaking with Mr. Perry he went into a little greater detail as to the many variables of shooting uphill vs downhill as to why that thier is no difference in the trajectory. He stated that without being adapted at advanc ed calculous one would not understand all of the math equations and many variables that goe into predicting trajectory. I asked him about programs that allow imput for positve and negative angles and Mr. Perry stated that if the program showed a difference in trajectory then it was incorrect.
Anyone that wants to ask Mr. Perry these question just go to his web site and get the contact info and ask away... It boils down to whom do you believe is correct and I believ that Exbal is IMHO.
Yes we should all keep this civil, and I applogize for my part..