code: def _embedding_classical_mds(matrix, dimensions=3, additive_correct=False):
      
      if additive_correct:
          dbc = double_centre(_additive_correct(matrix))
      else:
          dbc = double_centre(matrix)
      decomp = eigen(dbc)
      lambda_ = np.diag(np.sqrt(np.abs(decomp.vals[:dimensions])))
      evecs = decomp.vecs[:, :dimensions]
      coords = evecs.dot(lambda_)
      return coords
docs: Private method to calculate CMDS embedding
      :param dimensions: (int)
      :return: coordinate matrix (np.array)