docs: def _lmder1_watson():
      """Watson function (lmder1 test #11)"""
  
      def func(params, vec):
          div = (np.arange(29) + 1.) / 29
          s1 = 0
          dx = 1
  
          for j in range(1, params.size):
              s1 += j * dx * params[j]
              dx *= div
  
          s2 = 0
          dx = 1
  
          for j in range(params.size):
              s2 += dx * params[j]
              dx *= div
  
          vec[:29] = s1 - s2**2 - 1
          vec[29] = params[0]
          vec[30] = params[1] - params[0]**2 - 1
  
      def jac(params, jac):
          jac.fill(0)
          div = (np.arange(29) + 1.) / 29
          s2 = 0
          dx = 1
  
          for j in range(params.size):
              s2 += dx * params[j]
              dx *= div
  
          temp = 2 * div * s2
          dx = 1. / div
  
          for j in range(params.size):
              jac[j,:29] = dx * (j - temp)
              dx *= div
  
          jac[0,29] = 1
          jac[0,30] = -2 * params[0]
          jac[1,30] = 1
  
      _lmder1_driver(31, func, jac, np.zeros(6),
                     0.5477225575051661e+01, 0.4782959390976008e-01,
                     [-0.1572496150837816e-01, 0.1012434882329655e+01,
                      -0.2329917223876733e+00, 0.1260431011028184e+01,
                      -0.1513730313944205e+01, 0.9929972729184200e+00])
      _lmder1_driver(31, func, jac, np.zeros(6) + 10,
                     0.6433125789500264e+04, 0.4782959390969513e-01,
                     [-0.1572519013866769e-01, 0.1012434858601051e+01,
                      -0.2329915458438287e+00, 0.1260429320891626e+01,
                      -0.1513727767065747e+01, 0.9929957342632802e+00])
      _lmder1_driver(31, func, jac, np.zeros(6) + 100,
                     0.6742560406052133e+06, 0.4782959391154397e-01,
                     [-0.1572470197125856e-01, 0.1012434909256583e+01,
                      -0.2329919227616415e+00, 0.1260432929295546e+01,
                      -0.1513733204527065e+01, 0.9929990192232198e+00])
      _lmder1_driver(31, func, jac, np.zeros(9),
                     0.5477225575051661e+01, 0.1183114592124197e-02,
                     [-0.1530706441667223e-04, 0.9997897039345969e+00, 0.1476396349109780e-01,
                      0.1463423301459916e+00, 0.1000821094548170e+01, -0.2617731120705071e+01,
                      0.4104403139433541e+01, -0.3143612262362414e+01, 0.1052626403787590e+01],
                     decimal=8) # good enough for me
      _lmder1_driver(31, func, jac, np.zeros(9) + 10,
                     0.1208812706930700e+05, 0.1183114592125130e-02,
                     [-0.1530713348492787e-04, 0.9997897039412339e+00, 0.1476396297862168e-01,
                      0.1463423348188364e+00, 0.1000821073213860e+01, -0.2617731070847222e+01,
                      0.4104403076555641e+01, -0.3143612221786855e+01, 0.1052626393225894e+01],
                     decimal=7) # ditto
      _lmder1_driver(31, func, jac, np.zeros(9) + 100,
                     0.1269109290438338e+07, 0.1183114592123836e-02,
                     [-0.1530695233521759e-04, 0.9997897039583713e+00, 0.1476396251853923e-01,
                      0.1463423410963262e+00, 0.1000821047291639e+01, -0.2617731015736446e+01,
                      0.4104403014272860e+01, -0.3143612186025031e+01, 0.1052626385167739e+01],
                     decimal=7)
      # I've hacked params[0] below to agree with the Python since most everything else
      # is a lot closer. Fortran value is -0.6602660013963822D-08.
      _lmder1_driver(31, func, jac, np.zeros(12),
                     0.5477225575051661e+01, 0.2173104025358612e-04,
                     [-0.66380604e-08, 0.1000001644118327e+01, -0.5639321469801545e-03,
                      0.3478205400507559e+00, -0.1567315002442332e+00, 0.1052815158255932e+01,
                      -0.3247271095194506e+01, 0.7288434783750497e+01, -0.1027184809861398e+02,
                      0.9074113537157828e+01, -0.4541375419181941e+01, 0.1012011879750439e+01],
                     decimal=7)
      # These last two don't need any hacking or decimal < 10 ...
      _lmder1_driver(31, func, jac, np.zeros(12) + 10,
                     0.1922075897909507e+05, 0.2173104025185086e-04,
                     [-0.6637102230174097e-08, 0.1000001644117873e+01, -0.5639322083473270e-03,
                      0.3478205404869979e+00, -0.1567315039556524e+00, 0.1052815176545732e+01,
                      -0.3247271151521395e+01, 0.7288434894306651e+01, -0.1027184823696385e+02,
                      0.9074113643837332e+01, -0.4541375465336661e+01, 0.1012011888308566e+01],
                     decimal=7)
      _lmder1_driver(31, func, jac, np.zeros(12) + 100,
                     0.2018918044623666e+07, 0.2173104025398453e-04,
                     [-0.6638060464852487e-08, 0.1000001644117862e+01, -0.5639322103249589e-03,
                      0.3478205405035875e+00, -0.1567315040913747e+00, 0.1052815177180306e+01,
                      -0.3247271153370249e+01, 0.7288434897753017e+01, -0.1027184824108129e+02,
                      0.9074113646884637e+01, -0.4541375466608216e+01, 0.1012011888536897e+01])