code: def _IN_AutoMutualInfoStats_40_gaussian_fmmi(X_ac):
      # First minimum of the automutual information function.
      tau = int(min(40, np.ceil(len(X_ac) / 2)))
  
      diffs = np.zeros(tau - 1)
      prev = -0.5 * np.log(1 - np.power(X_ac[1], 2))
      for i in range(len(diffs)):
          corr = -0.5 * np.log(1 - np.power(X_ac[i + 2], 2))
          diffs[i] = corr - prev
          prev = corr
  
      for i in range(len(diffs) - 1):
          if diffs[i] * diffs[i + 1] < 0 and diffs[i] < 0:
              return i + 1
  
      return tau
  
imports: import math
  import numpy
  from sktime.utils.numba.njit import njit
label_desc: Use image node_id 27 for calling a global function with example usage: _IN_AutoMutualInfoStats_40_gaussian_fmmi(X_ac) and returns: tau, unknown