Hi - I'm trying to write a custom measurement in the classical spin mc code, and I'd like to be able to have the alps lattice library tell me the site that is at a given location relative to another site.

More specifically, I'd like to start with pair of sites, indices i and j, then compute the vector v=(r_j-r_i) (this I already know how to do using the coordinates function). Then, I'd like to go to some other site, k, and figure out the index, l, of the site at r_k + v (i.e. I want (r_l-r_k) = (r_j-r_i)). Is there a general way to do this using the alps lattice library or will I have to write special code for the particular lattice that I'm using? Thanks!