code: def powm(C, alpha):
      r"""Power of SPD/HPD matrices.
  
      The symmetric matrix power :math:`\alpha` of a SPD/HPD matrix
      :math:`\mathbf{C}` is defined by:
  
      .. math::
          \mathbf{D} =
          \mathbf{V} \left( \mathbf{\Lambda} \right)^{\alpha} \mathbf{V}^H
  
      where :math:`\mathbf{\Lambda}` is the diagonal matrix of eigenvalues
      and :math:`\mathbf{V}` the eigenvectors of :math:`\mathbf{C}`.
  
      Parameters
      ----------
      C : ndarray, shape (..., n, n)
          SPD/HPD matrices, at least 2D ndarray.
      alpha : float
          The power to apply.
  
      Returns
      -------
      D : ndarray, shape (..., n, n)
          Matrix power of C.
      """
  
      def power(x):
          return x**alpha
  
      return _matrix_operator(C, power)
  
file_path: pyRiemann/pyriemann/utils/base.py
imports: import numpy
  from numpy.core.numerictypes import typecodes
  from .test import is_pos_def
label_desc: Use image node_id 5 for calling a global function with example usage: powm(C, alpha) and returns: _matrix_operator, unknown