#define rosenbrocke_N         8 /* = p */

#define rosenbrocke_P         8 /* must be even */

static double rosenbrocke_x0[rosenbrocke_P] = { -1.2, 1.0, -1.2, 1.0,

                                                -1.2, 1.0, -1.2, 1.0 };

static double rosenbrocke_epsrel = 1.0e-12;

static void

rosenbrocke_checksol(const double x[], const double sumsq,

                     const double epsrel, const char *sname,

                     const char *pname)

{

  size_t i;

  const double sumsq_exact = 0.0;

  const double rosenbrocke_x[rosenbrocke_P] = { 1.0, 1.0, 1.0, 1.0,

                                                1.0, 1.0, 1.0, 1.0 };

  gsl_test_rel(sumsq, sumsq_exact, epsrel, "%s/%s sumsq",

               sname, pname);

  for (i = 0; i < rosenbrocke_P; ++i)

    {

      gsl_test_rel(x[i], rosenbrocke_x[i], epsrel, "%s/%s i=%zu",

                   sname, pname, i);

    }

}

static int

rosenbrocke_f (const gsl_vector * x, void *params, gsl_vector * f)

{

  size_t i;

  for (i = 0; i < rosenbrocke_N / 2; ++i)

    {

      double x2i = gsl_vector_get(x, 2*i + 1);

      double x2im1 = gsl_vector_get(x, 2*i);

      gsl_vector_set(f, 2*i, 10.0 * (x2i - x2im1*x2im1));

      gsl_vector_set(f, 2*i + 1, 1.0 - x2im1);

    }

  (void)params; /* avoid unused parameter warning */

  return GSL_SUCCESS;

}

static int

rosenbrocke_df (const gsl_vector * x, void *params, gsl_matrix * J)

{

  size_t i;

  gsl_matrix_set_zero(J);

  for (i = 0; i < rosenbrocke_N / 2; ++i)

    {

      double x2im1 = gsl_vector_get(x, 2*i);

      gsl_matrix_set(J, 2*i, 2*i, -20.0*x2im1);

      gsl_matrix_set(J, 2*i, 2*i + 1, 10.0);

      gsl_matrix_set(J, 2*i + 1, 2*i, -1.0);

    }

  (void)params; /* avoid unused parameter warning */

  return GSL_SUCCESS;

}

static int

rosenbrocke_fvv (const gsl_vector * x, const gsl_vector * v,

                 void *params, gsl_vector * fvv)

{

  size_t i;

  for (i = 0; i < rosenbrocke_N / 2; ++i)

    {

      double v2im1 = gsl_vector_get(v, 2*i);

      gsl_vector_set(fvv, 2*i, -20.0 * v2im1 * v2im1);

      gsl_vector_set(fvv, 2*i + 1, 0.0);

    }

  (void)x;      /* avoid unused parameter warning */

  (void)params; /* avoid unused parameter warning */

  return GSL_SUCCESS;

}

static gsl_multifit_nlinear_fdf rosenbrocke_func =

{

  rosenbrocke_f,

  rosenbrocke_df,

  rosenbrocke_fvv,

  rosenbrocke_N,

  rosenbrocke_P,

  NULL,

  0,

  0,

  0

};

static test_fdf_problem rosenbrocke_problem =

{

  "rosenbrock_extended",

  rosenbrocke_x0,

  NULL,

  NULL,

  &rosenbrocke_epsrel,

  &rosenbrocke_checksol,

  &rosenbrocke_func

};