Hello, Dr.Newville I attach the simple example you asked. It is the same 1 oxygen sphere, but without restraint and I simplified and got rid of macros Hfo1.chi is the spectrum. Feff0001.dat is the feff. Check_k.iff is the check in k space fit as was Check_r.iff is the check in r space fit. The result that I asked to check is program variable chi_square and manually calculated chi_square_calc. They aren't equal in both cases. I used chir_mag array in r space fit for a formula because couldn't get re and im arrays, there is something with flags or may be need to do fftf manually, but I didn't want to complicate the example. I will be very glad if you'd help me understand where are my formulae wrong when you could... Because I haven't got equivalent values even in r space, I'm not sure that r space will solve the problem of renormalization. If I simply didn't understand formulae, that's exactly why I tried to ask here to correct me as the user. Thanks a lot, Olga Kashurnikova