code: def _digamma_real(x):
      _intx = int(x)
      if _intx == x:
          if _intx <= 0:
              raise ZeroDivisionError("polygamma pole")
      if x < 0.5:
          x = 1.0 - x
          s = pi * cotpi(x)
      else:
          s = 0.0
      while x < 10.0:
          s -= 1.0 / x
          x += 1.0
      x2 = x**-2
      t = x2
      for c in _psi_coeff:
          s -= c * t
          if t < 1e-20:
              break
          t *= x2
      return s + math_log(x) - 0.5 / x
  
imports: import operator
  import math
  import cmath
label_desc: Use image node_id 17 for calling a global function with example usage: _digamma_real(x) and returns: unknown