Hi, all. I'll be brief. Can Airy functions [those who solve the differential equation y''-xy=0] be considered orthogonal over some interval? If so, what is their orthogonality condition? Given that the Airy functions have a representation in terms of Bessel functions, I would be inclined to think that the answer is yes; however, is there a compact form for their orthogonality condition? I've looked everywhere without success. Thanks.