trace.py 文件源码

def _is_scalar(e):
    """ Helper method used in Tr"""

    # sympify to set proper attributes
    e = sympify(e)
    if isinstance(e, Expr):
        if (e.is_Integer or e.is_Float or
            e.is_Rational or e.is_Number or
            (e.is_Symbol and e.is_commutative)
                ):
            return True

    return False