I was disappointed that my question about eigenfunctions of the fourier transform was closed so quickly. Given the ubiquity of the Fourier transform in physics, it seems like an excessively narrow view of "physics" to consider the question off-topic. Or should we direct all 'math methods' questions to math.SE?
I think that this site can benefit itself by allowing questions about mathematics which are directly related to physics. However, in the case of that particular question you're asking, it is a completely mathematical procedure in which the particular physics is not important to solve your problem.