class_docstr: Class for fitting the Diffusion Kurtosis Model
docstr: Initialize a DiffusionKurtosisFit class instance
  
  Since DKI is an extension of DTI, class instance is defined as subclass
  of the TensorFit from dti.py
  
  Parameters
  ----------
  model : DiffusionKurtosisModel Class instance
      Class instance containing the Diffusion Kurtosis Model for the fit
  model_params : ndarray (x, y, z, 27) or (n, 27)
  All parameters estimated from the diffusion kurtosis 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
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code: def __init__(self, model, model_params):
      """Initialize a DiffusionKurtosisFit class instance
  
      Since DKI is an extension of DTI, class instance is defined as subclass
      of the TensorFit from dti.py
  
      Parameters
      ----------
      model : DiffusionKurtosisModel Class instance
          Class instance containing the Diffusion Kurtosis Model for the fit
      model_params : ndarray (x, y, z, 27) or (n, 27)
      All parameters estimated from the diffusion kurtosis 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
  
      """
      TensorFit.__init__(self, model, model_params)
  
imports: import numpy
  import warnings
  import scipy.optimize
  import dipy.core.sphere
  from dipy.reconst.multi_voxel import multi_voxel_fit
  from dipy.reconst.dti import TensorFit, mean_diffusivity, from_lower_triangular, lower_triangular, decompose_tensor, MIN_POSITIVE_SIGNAL, nlls_fit_tensor, restore_fit_tensor
  from dipy.reconst.utils import dki_design_matrix
  from dipy.reconst.recspeed import local_maxima
  from dipy.reconst.base import ReconstModel
  from dipy.core.ndindex import ndindex
  from dipy.core.geometry import sphere2cart, cart2sphere, perpendicular_directions
  from dipy.core.optimize import PositiveDefiniteLeastSquares
  from dipy.data import get_sphere, get_fnames, load_sdp_constraints
  from dipy.reconst.vec_val_sum import vec_val_vect
  from dipy.core.gradients import check_multi_b
label_desc: Use image node_id 1 to create a new DiffusionKurtosisFit object from inherited base classes: TensorFit with example: obj = DiffusionKurtosisFit(model, model_params)