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# scipy.spatial.transform.Rotation.__pow__

Rotation.__pow__()

  Compose this rotation with itself n times.

  Composition of a rotation `p` with itself can be extended to non-integer `n` by considering the power `n` to be a scale factor applied to the angle of rotation about the rotation’s fixed axis. The expression `q = p ** n` can also be expressed as `q = Rotation.from_rotvec(n * p.as_rotvec())`.

  If `n` is negative, then the rotation is inverted before the power is applied. In other words, `p ** -abs(n) == p.inv() ** abs(n)`.

  Parameters:
    n float

      The number of times to compose the rotation with itself.

    modulus None

      This overridden argument is not applicable to Rotations and must be `None`.

  Returns:
    power `Rotation` instance

      If the input Rotation `p` contains `N` multiple rotations, then the output will contain `N` rotations where the `i` th rotation is equal to `p[i] ** n`

  Notes

  For example, a power of 2 will double the angle of rotation, and a power of 0.5 will halve the angle. There are three notable cases: if `n == 1` then the original rotation is returned, if `n == 0` then the identity rotation is returned, and if `n == -1` then `p.inv()` is returned.

  Note that fractional powers `n` which effectively take a root of rotation, do so using the shortest path smallest representation of that angle (the principal root). This means that powers of `n` and `1/n` are not necessarily inverses of each other. For example, a 0.5 power of a +240 degree rotation will be calculated as the 0.5 power of a -120 degree rotation, with the result being a rotation of -60 rather than +120 degrees.

  Examples

      >>> from scipy.spatial.transform import Rotation as R

  Raising a rotation to a power:

      >>> p = R.from_rotvec([1, 0, 0])
      >>> q = p ** 2
      >>> q.as_rotvec()
      array([2., 0., 0.])
      >>> r = p ** 0.5
      >>> r.as_rotvec()
      array([0.5, 0., 0.])

  Inverse powers do not necessarily cancel out:

      >>> p = R.from_rotvec([0, 0, 120], degrees=True)
      >>> ((p ** 2) ** 0.5).as_rotvec(degrees=True)
      array([  -0.,   -0., -60.])