## Initializing the Solver

Function: gsl_multifit_fsolver * gsl_multifit_fsolver_alloc (const gsl_multifit_fsolver_type * T, size_t n, size_t p)
  This function returns a pointer to a newly allocated instance of a solver of type T for n observations and p parameters.

  If there is insufficient memory to create the solver then the function returns a null pointer and the error handler is invoked with an error code of `GSL_ENOMEM`.

Function: gsl_multifit_fdfsolver * gsl_multifit_fdfsolver_alloc (const gsl_multifit_fdfsolver_type * T, size_t n, size_t p)
  This function returns a pointer to a newly allocated instance of a derivative solver of type T for n observations and p parameters. For example, the following code creates an instance of a Levenberg-Marquardt solver for 100 data points and 3 parameters,

      const gsl_multifit_fdfsolver_type * T
          = gsl_multifit_fdfsolver_lmder;
      gsl_multifit_fdfsolver * s
          = gsl_multifit_fdfsolver_alloc (T, 100, 3);

  If there is insufficient memory to create the solver then the function returns a null pointer and the error handler is invoked with an error code of `GSL_ENOMEM`.

Function: int gsl_multifit_fsolver_set (gsl_multifit_fsolver * s, gsl_multifit_function * f, gsl_vector * x)
  This function initializes, or reinitializes, an existing solver s to use the function f and the initial guess x.

Function: int gsl_multifit_fdfsolver_set (gsl_multifit_fdfsolver * s, gsl_function_fdf * fdf, gsl_vector * x)
  This function initializes, or reinitializes, an existing solver s to use the function and derivative fdf and the initial guess x.

Function: void gsl_multifit_fsolver_free (gsl_multifit_fsolver * s)
Function: void gsl_multifit_fdfsolver_free (gsl_multifit_fdfsolver * s)
  These functions free all the memory associated with the solver s.

Function: const char * gsl_multifit_fsolver_name (const gsl_multifit_fdfsolver * s)
Function: const char * gsl_multifit_fdfsolver_name (const gsl_multifit_fdfsolver * s)
  These functions return a pointer to the name of the solver. For example,

      printf("s is a '%s' solver\n",
             gsl_multifit_fdfsolver_name (s));

  would print something like `s is a 'lmder' solver`.