def rot_matrix(angle):
    r"""Rotation matrix

    This method produces a 2x2 rotation matrix for the given input angle.

    Parameters
    ----------
    angle : float
        Rotation angle in radians

    Returns
    -------
    np.ndarray 2x2 rotation matrix

    Examples
    --------
    >>> from modopt.math.matrix import rot_matrix
    >>> rot_matrix(np.pi / 6)
    array([[ 0.8660254, -0.5      ],
           [ 0.5      ,  0.8660254]])

    Notes
    -----
    Implements the following equation:

    .. math::
        R(\theta) = \begin{bmatrix}
            \cos(\theta) & -\sin(\theta) \\
            \sin(\theta) & \cos(\theta)
        \end{bmatrix}

    """

    return np.around(np.array([[np.cos(angle), -np.sin(angle)],
                     [np.sin(angle), np.cos(angle)]], dtype='float'), 10)