anticommutator.py 文件源码

def eval(cls, a, b):
        if not (a and b):
            return S.Zero
        if a == b:
            return Integer(2)*a**2
        if a.is_commutative or b.is_commutative:
            return Integer(2)*a*b

        # [xA,yB]  ->  xy*[A,B]
        # from sympy.physics.qmul import QMul
        ca, nca = a.args_cnc()
        cb, ncb = b.args_cnc()
        c_part = ca + cb
        if c_part:
            return Mul(Mul(*c_part), cls(Mul._from_args(nca), Mul._from_args(ncb)))

        # Canonical ordering of arguments
        #The Commutator [A,B] is on canonical form if A < B.
        if a.compare(b) == 1:
            return cls(b, a)