code: def test_special_values():
      # Test special values from Gauss's digamma theorem. See
      #
      # https://en.wikipedia.org/wiki/Digamma_function
  
      dataset = [
          (1, -euler),
          (0.5, -2 * log(2) - euler),
          (1 / 3, -pi / (2 * sqrt(3)) - 3 * log(3) / 2 - euler),
          (1 / 4, -pi / 2 - 3 * log(2) - euler),
          (
              1 / 6,
              -pi * sqrt(3) / 2 - 2 * log(2) - 3 * log(3) / 2 - euler,
          ),
          (
              1 / 8,
              -pi / 2
              - 4 * log(2)
              - (pi + log(2 + sqrt(2)) - log(2 - sqrt(2))) / sqrt(2)
              - euler,
          ),
      ]
  
      dataset = np.asarray(dataset)
      FuncData(sc.digamma, dataset, 0, 1, rtol=1e-14).check()
  
file_path: scipy/scipy/special/tests/test_digamma.py
imports: import numpy
  from numpy import pi, log, sqrt
  from numpy.testing import assert_, assert_equal
  from scipy.special._testutils import FuncData
  import scipy.special
label_desc: Use image node_id 2 for calling a global function with example usage: test_special_values() without return types