code: def ac2poly(data):
      
      a, e, _c = LEVINSON(data)
      a = numpy.insert(a, 0, 1)
      return a, e
docs: Convert autocorrelation sequence to prediction polynomial
  
      :param array data:    input data (list or numpy.array)
      :return:
          * AR parameters
          * noise variance
  
      This is an alias to::
  
          a, e, c = LEVINSON(data)
  
      :Example:
  
      .. doctest::
  
          >>> from spectrum import ac2poly
          >>> from numpy import array
          >>> r = [5, -2, 1.01]
          >>> ar, e = ac2poly(r)
          >>> ar
          array([ 1.  ,  0.38, -0.05])
          >>> e
          4.1895000000000007