Base class of all multi-dimensional function classes which are used for fitting. The function has an independent variable 'x' (the argument to evaluate_f), a dependent variable 'y' (the result of evaluate_f) and a number of function parameters. To use this class, derive from it and overload the virtual functions 'evaluate_f' (function value), 'evaluate_df' (first derivative), 'numof_fitpars', and 'get_fitpar'. Parameters which are modified during the fit should be members of type fitpar.
Definition at line 76 of file fitting.h.