docstr: Diffusion tensor's outer product with itself.
  
  Returns
  -------
  d_sq : numpy.ndarray
docstr_tok: ["Diffusion","tensor","'s","outer","product","with","itself",".","Returns","--","--","--","-","d_sq",":","numpy.ndarray"]
code: def d_sq(self):
      """Diffusion tensor's outer product with itself.
  
      Returns
      -------
      d_sq : numpy.ndarray
      """
      d_sq = np.matmul(
          self.params[..., 1:7, np.newaxis],
          self.params[..., np.newaxis, 1:7],
      )
      return d_sq
  
imports: from warnings import warn
  import numpy
  from dipy.reconst.base import ReconstModel
  from dipy.reconst.dti import auto_attr
  from dipy.utils.optpkg import optional_package
label_desc: Use image node_id 8 for calling the QtiFit obj's underlying member method code with example usage: obj.d_sq() and returns: d_sq