docstr: Normalized variance of mean diffusivities.
  
  Returns
  -------
  c_md : numpy.ndarray
  
  Notes
  -----
  Normalized variance of microscopic mean diffusivities is calculated as
  
      .. math::
  
          C_      ext{MD} = rac{\mathbb{C} : \mathbb{E}_ ext{bulk}}
          {\langle \mathbf{D} \otimes \mathbf{D} 
  angle :
          \mathbb{E}_     ext{bulk}}
docstr_tok: ["Normalized","variance","of","mean","diffusivities",".","Returns","--","--","--","-","c_md",":","numpy.ndarray","Notes","--","--","-","Normalized","variance","of","microscopic","mean","diffusivities","is","calculated","as","..","math",":",":","C_","ext","{","MD","}","=","rac","{","\\mathbb","{","C","}",":","\\mathbb","{","E","}","_","ext","{","bulk","}","}","{","\\langle","\\mathbf","{","D","}","\\otimes","\\mathbf","{","D","}","angle",":","\\mathbb","{","E","}","_","ext","{","bulk","}","}"]
code: def c_md(self):
      """Normalized variance of mean diffusivities.
  
      Returns
      -------
      c_md : numpy.ndarray
  
      Notes
      -----
      Normalized variance of microscopic mean diffusivities is calculated as
  
          .. math::
  
              C_\text{MD} = \frac{\mathbb{C} : \mathbb{E}_\text{bulk}}
              {\langle \mathbf{D} \otimes \mathbf{D} \rangle :
              \mathbb{E}_\text{bulk}}
      """
      c_md = (
          self.v_md
          / np.matmul(
              np.swapaxes(from_6x6_to_21x1(self.mean_d_sq), -1, -2),
              from_6x6_to_21x1(E_bulk),
          )[..., 0, 0]
      )
      return c_md
  
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 10 for calling the QtiFit obj's underlying member method code with example usage: obj.c_md() and returns: c_md