Python中的自定义函数问题

Question

输入x值，按下式计算并输出S值。要求
(1)末项小于10-5时结束求和;
(2)阶乘采用自定义函数过程实现
s=1+x/1!+x∧2/2!＋…+x∧n/n!

Answer 1

def fact(n):
    s = 1
    for i in range(1,n+1):
        s *= i
    return s

x = eval(input())
s = 1
a = 1
i = 1
while a >= pow(10,-5):
    a = pow(x,i)/fact(i)
    s += a
    i += 1
print(s)