code: def split_cti_params(cti_params):
      r"""Splits CTI params into DTI, DKI, CTI portions.
  
      Extract the diffusion tensor eigenvalues, the diffusion tensor
      eigenvector matrix, and the 21 independent elements of the covariance
      tensor, and the 15 independent elements of the kurtosis tensor from the
      model parameters estimated from the CTI model
  
      Parameters
      ----------
          params: numpy.ndarray (..., 48)
          All parameters estimated from the correlation tensor model.
          Parameters are ordered as follows:
  
              1. Three diffusion tensor's eigenvalues
              2. Three lines of the eigenvector matrix each containing the
              first, second and third coordinates of the eigenvector
              3. Fifteen elements of the kurtosis tensor
              4. Twenty-One elements of the covariance tensor
  
      Returns
      -------
      evals : array (..., 3)
          Eigenvalues from eigen decomposition of the tensor.
      evecs : array (..., 3)
          Associated eigenvectors from eigen decomposition of the tensor.
          Eigenvectors are columnar (e.g. evecs[:,j] is associated with
          evals[j])
      kt : array (..., 15)
          Fifteen elements of the kurtosis tensor
      ct: array(..., 21)
          Twenty-one elements of the covariance tensor
      """
      evals = cti_params[..., :3]
      evecs = cti_params[..., 3:12].reshape(
          cti_params.shape[:-1] + (3, 3)
      )
      kt = cti_params[..., 12:27]
      ct = cti_params[..., 27:48]
      return evals, evecs, kt, ct
  
imports: import numpy
  from dipy.reconst.multi_voxel import multi_voxel_fit
  from dipy.reconst.base import ReconstModel
  from dipy.reconst.utils import cti_design_matrix
  from dipy.reconst.dki import DiffusionKurtosisFit
  from dipy.reconst.dti import decompose_tensor, from_lower_triangular, lower_triangular, MIN_POSITIVE_SIGNAL
  from dipy.core.onetime import auto_attr
label_desc: Use image node_id 3 for calling a global function with example usage: split_cti_params(cti_params) and returns: evals,  evecs,  kt,  ct