Function gsl_sys::gsl_multifit_fdfsolver_dif_fdf

pub unsafe extern "C" fn gsl_multifit_fdfsolver_dif_fdf(
    x: *const gsl_vector, 
    fdf: *mut gsl_multifit_function_fdf, 
    f: *mut gsl_vector, 
    J: *mut gsl_matrix
) -> c_int