python 的lambda函数怎么输出

Question

要求是Input:
n = 6
pmt = 400
discount_rate = 0.12
Expected output:
Call pv_ordinary_annuity8(pmt,n,discount_rate) function
=>> Output: 1644.56

我写的是
n = 6
pmt = 400
discount_rate = 0.12

pv = lambda pmt , discount_rate, n:{pmt*((1-(1/(1+discount_rate)**n))/discount_rate)}

print(pv)

但是输出的是<function at 0x000001BB43783430>
并没有输出结果
请问哪里错了

Answer 1

pv是函数，试试

print(pv(pmt, discount_rate, n))

另外lambda函数中不需要加大括号的，这样导致返回的是一个集合，可改成：

pv = lambda pmt , discount_rate, n: round(pmt*((1-(1/(1+discount_rate)**n))/discount_rate), 2)