def quaternion_imag(quaternion):
    """Return imaginary part of quaternion.

    >>> quaternion_imag([3, 0, 1, 2])
    array([ 0.,  1.,  2.])

    """
    return numpy.array(quaternion[1:4], dtype=numpy.float64, copy=True)
Return imaginary part of quaternion.

    >>> quaternion_imag([3, 0, 1, 2])
    array([ 0.,  1.,  2.])