text: '''
  The  sp.pmt() function is used to answer the following question: What is the monthly
  cash flow to pay off a mortgage of $250,000 over 30 years with an annual percentage
  rate (APR) of 4.5 percent, compounded monthly?
  '''
  import scipy as sp
  
  '''
  贷款:200'000.00
  年利率：5%
  还款周期：月
  贷款年限：3年
  每月还款：5'994.18
  '''
  payment2 = sp.pmt(0.05/12,3*12,200000,fv=0,when='end')
  print (payment2)