docs: def _lmder1_rosenbrock():
      """Rosenbrock function (lmder test #4)"""
  
      def func(params, vec):
          vec[0] = 10 * (params[1] - params[0]**2)
          vec[1] = 1 - params[0]
  
      def jac(params, jac):
          jac[0,0] = -20 * params[0]
          jac[0,1] = -1
          jac[1,0] = 10
          jac[1,1] = 0
  
      guess = np.asfarray([-1.2, 1])
      norm1s = [0.491934955050e+01, 0.134006305822e+04, 0.1430000511923e+06]
  
      for i in range(3):
          _lmder1_driver(2, func, jac, guess * 10**i,
                         norm1s[i], 0, [1, 1])