def clebsch_gordan(j_1, j_2, j_3, m_1, m_2, m_3):
    r"""
    Calculates the Clebsch-Gordan coefficient
    `\langle j_1 m_1 \; j_2 m_2 | j_3 m_3 \rangle`.

    The reference for this function is [Edmonds74]_.

    INPUT:

    -  ``j_1``, ``j_2``, ``j_3``, ``m_1``, ``m_2``, ``m_3`` - integer or half integer

    OUTPUT:

    Rational number times the square root of a rational number.

    EXAMPLES::

        >>> from sympy import S
        >>> from sympy.physics.wigner import clebsch_gordan
        >>> clebsch_gordan(S(3)/2, S(1)/2, 2, S(3)/2, S(1)/2, 2)
        1
        >>> clebsch_gordan(S(3)/2, S(1)/2, 1, S(3)/2, -S(1)/2, 1)
        sqrt(3)/2
        >>> clebsch_gordan(S(3)/2, S(1)/2, 1, -S(1)/2, S(1)/2, 0)
        -sqrt(2)/2

    NOTES:

    The Clebsch-Gordan coefficient will be evaluated via its relation
    to Wigner 3j symbols:

    .. math::

        \langle j_1 m_1 \; j_2 m_2 | j_3 m_3 \rangle
        =(-1)^{j_1-j_2+m_3} \sqrt{2j_3+1}
        \operatorname{Wigner3j}(j_1,j_2,j_3,m_1,m_2,-m_3)

    See also the documentation on Wigner 3j symbols which exhibit much
    higher symmetry relations than the Clebsch-Gordan coefficient.

    AUTHORS:

    - Jens Rasch (2009-03-24): initial version
    """
    res = (-1) ** sympify(j_2 + m_3 - j_1) * sqrt(2 * j_3 + 1) * \
        wigner_3j(j_1, j_2, j_3, m_1, m_2, -m_3)
    return res
dataset/ETHPy150Open sympy/sympy/sympy/physics/wigner.py/clebsch_gordan/swapped operands of `-`