code: def Cmatrix(x, y, sx, sy, theta):
      
      C = np.vstack([elliptical_gaussian(x, y, 1, i, j, sx, sy, theta) for i, j in zip(x, y)])
      return C
docs: Construct a correlation matrix corresponding to the data.
      The matrix assumes a gaussian correlation function.
  
      Parameters
      ----------
      x, y : array-like
          locations at which to evaluate the correlation matirx
      sx, sy : float
          major/minor axes of the gaussian correlation function (sigmas)
  
      theta : float
          position angle of the gaussian correlation function (degrees)
  
      Returns
      -------
      data : array-like
          The C-matrix.