I've run across a system of recursive functions (call them f and g). The system looks like this: f(x) = a f(x-1) + b g(x-1) g(x) = a g(x-1) + c f(x-1) I also know that f(0) = 0 and g(0)>0. Finally, I know for other reasons that are too complicated to go into here that the system is somehow related to the trig functions. This is well outside my area of expertise, so I'm hopeful one of you can point me in the right direction so that I can perhaps simplify the system. Thanks in advance.