Preliminary exploration of the mathematical method for fitting line profiles.

In the course of the fitting of line profiles, the objective function is highly non-linear and has more fitting parameters because of the asymmetry of line profiles, and therefore the domain of definition of the fitting parameters need to be restricted. In this paper, the non-linear objective function is treated by means of the complete linearization method and the fitting parameters are restricted by using the punished function. Finally, the asymmetrical lines of the loop prominence of 1984 February 18 are fitted according to this method.