code: def rc2ac(k, R0):
      
      [a,efinal] = rc2poly(k, R0)
      R, u, kr, e = rlevinson(a, efinal)
      return R
docs: Convert reflection coefficients to autocorrelation sequence.
  
      :param k: reflection coefficients
      :param R0: zero-lag autocorrelation
      :returns: the autocorrelation sequence
  
      .. seealso:: :func:`ac2rc`, :func:`poly2rc`, :func:`ac2poly`, :func:`poly2rc`, :func:`rc2poly`.