1. The problem statement, all variables and given/known data I'm reading something in my quantum physics book that says given a wavefunction ψ that is even, if we evaluate its integral from -ε to ε, the integral is 0. How can this be? I thought this is the property of odd functions. 2. Relevant equations ψ=Aekx if x<0 and ψ=Be-kx if x>0, ε is infinitesimal change in x 3. The attempt at a solution By boundary conditions, say at the origin, this will give A=B then the book says we can represent the wave function as ψ=Ae-k|x|. The wave function is even so the integral is 0 between -ε to ε.