I'm trying to make a simple demo of how mic polar patterns work. Everything is fine and according plan, except I can't get LCD to draw the negative lobe of the mic correctly. I've been through it, so whatever it is either I don't know or I can't see. It looks to me like the numbers from the equations are right, but somewhere in the LCD is the problem-- It simply draws the negative lobe of the pattern correctly, but on the positive side of the graph.
Profuse thanks for any clues here.
(Sorry about the size, I tried to take out everything I could.)