code: def stationary_solve(r, b):
      """
      Solve a linear system for a Toeplitz correlation matrix.
  
      A Toeplitz correlation matrix represents the covariance of a
      stationary series with unit variance.
  
      Parameters
      ----------
      r : array_like
          A vector describing the coefficient matrix.  r[0] is the first
          band next to the diagonal, r[1] is the second band, etc.
      b : array_like
          The right-hand side for which we are solving, i.e. we solve
          Tx = b and return b, where T is the Toeplitz coefficient matrix.
  
      Returns
      -------
      The solution to the linear system.
      """
  
      db = r[0:1]
  
      dim = b.ndim
      if b.ndim == 1:
          b = b[:, None]
      x = b[0:1, :]
  
      for j in range(1, len(b)):
          rf = r[0:j][::-1]
          a = (b[j, :] - np.dot(rf, x)) / (1 - np.dot(rf, db[::-1]))
          z = x - np.outer(db[::-1], a)
          x = np.concatenate((z, a[None, :]), axis=0)
  
          if j == len(b) - 1:
              break
  
          rn = r[j]
          a = (rn - np.dot(rf, db)) / (1 - np.dot(rf, db[::-1]))
          z = db - a * db[::-1]
          db = np.concatenate((z, np.r_[a]))
  
      if dim == 1:
          x = x[:, 0]
  
      return x
  
imports: import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: stationary_solve(r, b) and returns: x