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# numpy.linalg.matrix_power

`numpy.linalg.``matrix_power`(M, n)

  Raise a square matrix to the (integer) power n.

  For positive integers n, the power is computed by repeated matrix squarings and matrix multiplications. If `n == 0`, the identity matrix of the same shape as M is returned. If `n < 0`, the inverse is computed and then raised to the `abs(n)`.

  Parameters : | M : ndarray or matrix object Matrix to be “powered.” Must be square, i.e. `M.shape == (m, m)`, with m a positive integer. n : int The exponent can be any integer or long integer, positive, negative, or zero.
  Returns : | M**n : ndarray or matrix object The return value is the same shape and type as M; if the exponent is positive or zero then the type of the elements is the same as those of M. If the exponent is negative the elements are floating-point.
  Raises : | LinAlgError : If the matrix is not numerically invertible.

  See also

  `matrix`
    Provides an equivalent function as the exponentiation operator (`**`, not `^`).

  Examples

      >>> from numpy import linalg as LA
      >>> i = np.array([[0, 1], [-1, 0]]) # matrix equiv. of the imaginary unit
      >>> LA.matrix_power(i, 3) # should = -i
      array([[ 0, -1],
             [ 1,  0]])
      >>> LA.matrix_power(np.matrix(i), 3) # matrix arg returns matrix
      matrix([[ 0, -1],
              [ 1,  0]])
      >>> LA.matrix_power(i, 0)
      array([[1, 0],
             [0, 1]])
      >>> LA.matrix_power(i, -3) # should = 1/(-i) = i, but w/ f.p. elements
      array([[ 0.,  1.],
             [-1.,  0.]])

  Somewhat more sophisticated example

      >>> q = np.zeros((4, 4))
      >>> q[0:2, 0:2] = -i
      >>> q[2:4, 2:4] = i
      >>> q # one of the three quarternion units not equal to 1
      array([[ 0., -1.,  0.,  0.],
             [ 1.,  0.,  0.,  0.],
             [ 0.,  0.,  0.,  1.],
             [ 0.,  0., -1.,  0.]])
      >>> LA.matrix_power(q, 2) # = -np.eye(4)
      array([[-1.,  0.,  0.,  0.],
             [ 0., -1.,  0.,  0.],
             [ 0.,  0., -1.,  0.],
             [ 0.,  0.,  0., -1.]])

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