Create DCM (Matrix3) from euler angles
        :param euler: array [roll, pitch, yaw] in rad
        :returns: Matrix3

def _euler_to_dcm(self, euler):
        """
        Create DCM (Matrix3) from euler angles
        :param euler: array [roll, pitch, yaw] in rad
        :returns: Matrix3
        """
        assert(len(euler) == 3)
        m = Matrix3()
        m.from_euler(*euler)
        return m