## Iteration

The following functions drive the iteration of each algorithm. Each function performs one iteration to update the state of any solver of the corresponding type. The same functions work for all solvers so that different methods can be substituted at runtime without modifications to the code.

Function: int gsl_multifit_fsolver_iterate (gsl_multifit_fsolver * s)
Function: int gsl_multifit_fdfsolver_iterate (gsl_multifit_fdfsolver * s)
  These functions perform a single iteration of the solver s. If the iteration encounters an unexpected problem then an error code will be returned. The solver maintains a current estimate of the best-fit parameters at all times. This information can be accessed with the following auxiliary functions,

Function: gsl_vector * gsl_multifit_fsolver_position (const gsl_multifit_fsolver * s)
Function: gsl_vector * gsl_multifit_fdfsolver_position (const gsl_multifit_fdfsolver * s)
  These functions return the current position (i.e. best-fit parameters) of the solver s.