I have this function f(x)=e^-Cos(x) that has a definite area underneath on every interval, but specifically on [0,2pi] or any intercal of 2pi. When I try to integrate it I get two functions I have never even heard of, and when I use N to get an approximation it is half the right number. I know I can just use NIntegrate, but I don't know how to get precision up with that. I don't need help on this badly as it is only a personal endeavor, but it would be appreciated.
Attachment: e^-Cos[x].nb, URL: ,