complexes.py 文件源码

def eval(cls, arg):
        from sympy.simplify.simplify import signsimp
        if hasattr(arg, '_eval_Abs'):
            obj = arg._eval_Abs()
            if obj is not None:
                return obj
        # handle what we can
        arg = signsimp(arg, evaluate=False)
        if arg.is_Mul:
            known = []
            unk = []
            for t in arg.args:
                tnew = cls(t)
                if tnew.func is cls:
                    unk.append(tnew.args[0])
                else:
                    known.append(tnew)
            known = Mul(*known)
            unk = cls(Mul(*unk), evaluate=False) if unk else S.One
            return known*unk
        if arg is S.NaN:
            return S.NaN
        if arg.is_zero:  # it may be an Expr that is zero
            return S.Zero
        if arg.is_nonnegative:
            return arg
        if arg.is_nonpositive:
            return -arg
        if arg.is_imaginary:
            arg2 = -S.ImaginaryUnit * arg
            if arg2.is_nonnegative:
                return arg2
        if arg.is_real is False and arg.is_imaginary is False:
            from sympy import expand_mul
            return sqrt( expand_mul(arg * arg.conjugate()) )
        if arg.is_Pow:
            base, exponent = arg.as_base_exp()
            if exponent.is_even and base.is_real:
                return arg
            if exponent.is_integer and base is S.NegativeOne:
                return S.One