code: def revrt(X, m=None):
      """
      Inverse of forrt. Equivalent to Munro (1976) REVRT routine.
      """
      if m is None:
          m = len(X)
      i = int(m // 2 + 1)
      y = X[:i] + np.r_[0, X[i:], 0] * 1j
      return np.fft.irfft(y) * m
  
imports: import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: revrt(X, m) and returns: unknown