Hi all, Please, help me. When I try to do any fit in Arthemis, setting all parameters unless one, been this one any of the parameters, the fit gives for the answer -1.0000 +/- 0.000000 like example down. What is happening? ============================================================ Independent points = 8.239257812 Number of variables = 1.000000000 Chi-square = 0.120000000E+37 Reduced Chi-square = 0.165762849E+36 R-factor = NaN Measurement uncertainty (k) = 0.000437667 Measurement uncertainty (R) = 0.000724906 Number of data sets = 1.000000000 Guess parameters +/- uncertainties (initial guess): * amp = -1.0000000 +/- 0.0000000 (1.0000)* Set parameters: enot = 0 delr = 0 ss = 0.003 c3 = 0.0001 c4 = 0.00001 -- Kleper de Oliveira Rocha Chemical Engenieer Doctorated Tels. 55 016 3351-8694