I get how to do them, I just have one question. An example that my prof. handed out has this: With the f(x) being 0 from -pi to 0, 1 from 0 to pi/2 and 0 from pi/2 to pi. But my question is when he has the last line in that picture. He has e^-ipi -> 1? I'm not understanding that step he's doing there. I'm doing the first problem in the complex Fourier series section of the homework and I can't seem to simplify anything, so I'm guessing I'm missing some crucial relation here. EDIT: Actually, I have no idea what the "n=m" part is either. I don't see "m" anywhere in the book.