The CLASS user may analyse spectra by fitting profiles. The fitting commands are available from the FIT language. The minimization method is taken from the MINUIT system of CERN, modified and optimized for this purpose. Reliability proved to be good. Five types of profiles are presently available, and can be selected by the METHOD command:
Code, Intensity, Code, Position, Code, Width, [Code, Parameter 4]The code is an integer number between 0 and 4. Note that, though the program works on the area (or other quantities as for NH3 methods), you have to give the intensity, since this quantity is more intuitive than area. The use of the list directed format makes things easier when only one parameter has to be modified (cf Fortran norms). The number of lines N may be zero; in this case the program finds out reasonable starting values by itself.
Values may be also entered graphically if the cursor is available. After entering LINES N, first point the cursor to one side of the line, strike one key, point the cursor the other side, strike another key. The program computes the moment of the spectrum between these boundaries and use it to set up starting values. Proceed like this for all components. One drawback of this way of entering values is that you cannot change the control codes. It should be used only for entirely independent and free lines.