Python中的 numpy.nper()

numpy.pmt(rate, pmt, pv, fv, when = 'end') ：此财务函数可帮助用户计算定期付款的数量。

Parameters :
rate : [scalar or (M, )array] Rate of interest as decimal (not per cent) per period
pmt : [scalar or (M, )array] Payment value
fv : [scalar or (M, )array] Future value
pv : [scalar or (M, )array] present value
when : at the beginning (when = {‘begin’, 1}) or the end (when = {‘end’, 0}) of each period. Default is {‘end’, 0}.

Return : Number of periodic payments.

正在求解的方程：

fv + pv*(1+rate)**nper + pmt*(1 + rate*when)/rate*((1 + rate)**nper – 1) == 0

or when rate == 0
fv + pv + pmt * nper == 0

代码：

# Python program explaining 
# pmt() function 
  
import numpy as np 
  
''' 
Question : 
  
how much time would it take to pay-off a loan of 
$10, 000 at 10 % annual rate of interest, if we had 
$100 to pay each month ? 
'''
  
# rate    pmt    pv 
Solution = np.nper(0.1 / 12, -100, 10000) 
  
# Here fv = 0 ; Also Default value of fv = 0 
print("Solution - No. of periods : % f months" %(Solution)) 

输出：

Solution - No. of periods : 215.905777 months