1. The problem statement, all variables and given/known data Integrate exp(-z^2) over the rectangle with vertices at 0, R, R + ia, and ia. 2. Relevant equations int(0, inf)(exp(-x^2)) = sqrt(pi/2) 3. The attempt at a solution I really don't have much of an idea here - the function is analytic so has no residues... The part from 0 to R is just the real integral, but for the other 3 sides I'm not too sure on how to proceed.