在家宅久了，想写点代码，算什么好呢？算算LPR吧
这有啥算头？
算固定利率和LPR哪个划算？算等额本息和等额本金哪种方式划算：我们要用总还款的当前币值折现值（未来花的钱相当于现在支出多少）来比较，还要在不同通胀情况下的折现值来体现各种方式的特点。
下面就让我来算算吧，有错请朋友们不吝指教~~
——————————————————————————正文分割线————————————————————
公式介绍：
LPR切换前，使用固定利率（当前是4.75%）——
等额本息还款方式：月供=本金*月利率*（1+月利率）^总贷款月数/[（1+月利率）^总贷款月数-1]
等额本金还款方式：月供=本金/总贷款月数+剩余本金*月利率
LPR切换后，使用浮动利率（这里就先考虑一年调整一次LPR的方式）——
等额本息还款方式(每年一调)：月供=年剩余本金*LPR*（1+LPR）^(剩余年月数)/[（1+LPR）^(剩余年月数)-1]
等额本金还款方式：月供=本金/总贷款月数+剩余本金*LPR
注意的是：
每月所还的利息部分=贷款剩余本金*月利率
每月所还本金部分=月供-每月所还的利息部分
公式参考来源（有更好的信息请补充更正~）：
https://www.cnblogs.com/lixuwu/p/11125517.html
https://zhidao.baidu.com/question/428849979409866612.html
https://www.u8see.com/housetool.asp
https://zhidao.baidu.com/question/487889702484427292.html
https://www.rong360.com/baike/21.html#3
——————————————————————————公式升级————————————————————
我们关心的是总还款的折现值，所以现在给出计算公式：
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以200万贷款，30年还款为例，当前利率4.75%，未来通胀率等于LPR 的整数倍（实际有不同说法，是否线性关系也请专业朋友指教？），而LPR的调整方向分为3种——不变，降低，升高
下表是计算结果的统计表格：
根据表格，我的结论是：
1、通胀率有几种表述——统计局给的CPI指数/央行统计的通胀率/实际购买力缩减程度——大概率当前的经济情况和全球的低利率趋势，通胀率可能出现较大值，因此，我个人愿意取更大的通胀率结果。
2、通胀率>LPR，LPR增大 优于 LPR锁定 优于LPR降低（非常反直觉！！！！！！！！也和网上的专家说的不一样！！请有不同意见的同学来拍砖！）
3、等额本息 整体优于 等额本金
4、除了考虑折现款总额，还要看还款金额的变化趋势，对当前家庭现金流的影响，如果有投资理财，还要考虑投资回报率来决定现金流最优方式。
5、LPR下降，等额本息月供减少，等额本金月供减少加快。LPR上升，等额本息月供增加，等额本金月供减少变慢。通胀率对月供无影响。月供对家庭现金流的影响受到还款方式和LPR决定。
| 本金 | 还款方式 | LPR月利率/通胀率 | 月供 | 总还款 |
总折现款（按LPR通胀） |
总折现款（按通胀率=2*LPR） | 总折现款（按通胀率=4*LPR） | |
| 200万 | 等额本息 | 不变4.75% | 10432 | 3755860 | 2000000 | 1240755 | 656617 | |
| 降低4.75%匀降到0.5% | 10432~7958 | 3172902 | 1999997 | 1343253 | 724197 | |||
| 升高4.75%匀升到8% | 10432~12655 | 4257985 | 2000000 | 1191228 | 631003 | |||
| 等额本金 | 不变4.75% | 13472~5577 | 3428958 | 2000000 | 1330351 | 762237 | ||
| 降低4.75%匀降到0.5% | 13472~5558 | 3026684 | 2000000 | 1405184 | 814889 | |||
| 升高4.75%匀升到8% | 13472~5592 | 3736579 | 2000000 | 1295439 | 741351 |
|
下面是代码链接：
https://github.com/yangh2333/-House-property-/blob/master/CalculateHousingLoan
下面是上述表格统计的情况的运行结果：
+++++++++++++++++++++++++++++++++++++等额本息++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++ 通胀率=LPR++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.0475
inflation rate times is 1
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 10432.946730061847
total payedback is 3755860.8228223836
total conversion back is: 2000000.0000000116
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.005
inflation rate times is 1
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 7958.323764604197
total payedback is 3172902.8315327065
total conversion back is: 1999997.7040952134
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.08
inflation rate times is 1
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 12655.590181551723
total payedback is 4257985.192792086
total conversion back is: 2000000.9518129409
-------------end------------------------
分析：LPR下行，月供会减少，以后每月的家庭流水压力逐渐减小。LPR上行，月供增加，流水压力逐渐增加，但是幅度比较温和。总之，和大通胀比起来都算很小的涨幅。
+++++++++++++++++++++++++++++++++++++等额本息+++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++ 通胀率=2*LPR++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.0475
inflation rate times is 2
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 10432.946730061847
total payedback is 3755860.8228223836
total conversion back is: 1240755.7268539048
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.005
inflation rate times is 2
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 7958.323764604197
total payedback is 3172902.8315327065
total conversion back is: 1343253.0812919503
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.08
inflation rate times is 2
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 12655.590181551723
total payedback is 4257985.192792086
total conversion back is: 1191228.1835512465
-------------end------------------------
+++++++++++++++++++++++++++++++++++++等额本息+++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++ 通胀率=4*LPR++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.0475
inflation rate times is 4
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 10432.946730061847
total payedback is 3755860.8228223836
total conversion back is: 656617.5359742445
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.005
inflation rate times is 4
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 7958.323764604197
total payedback is 3172902.8315327065
total conversion back is: 724197.0108411231
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus_and_interest
LPR change forme 0.0475 to 0.08
inflation rate times is 4
-------------result----------------------
0 year 0 month monthly_payback= 10432.946730062275
29 year 11 month monthly_payback= 12655.590181551723
total payedback is 4257985.192792086
total conversion back is: 631003.4974365009
-------------end------------------------
分析：通胀不影响月供金额数字。
+++++++++++++++++++++++++++++++++++++等额本金+++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++ 通胀率=LPR+++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.0475
inflation rate times is 1
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5577.546296296348
total payedback is 3428958.3333333456
total conversion back is: 2000000.0000000165
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.005
inflation rate times is 1
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5558.526234567908
total payedback is 3026684.0277777864
total conversion back is: 2000000.0000000086
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.08
inflation rate times is 1
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5592.091049382803
total payedback is 3736579.8611111296
total conversion back is: 2000000.0000000056
-------------end------------------------
分析：等额本金下，LPR降低，月供加速减少。LPR升高，月供减缓减少。
+++++++++++++++++++++++++++++++++++++等额本金++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++ 通胀率=2*LPR++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.0475
inflation rate times is 2
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5577.546296296348
total payedback is 3428958.3333333456
total conversion back is: 1330351.8914530918
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.005
inflation rate times is 2
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5558.526234567908
total payedback is 3026684.0277777864
total conversion back is: 1405184.0172224122
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.08
inflation rate times is 2
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5592.091049382803
total payedback is 3736579.8611111296
total conversion back is: 1295439.227252862
-------------end------------------------
+++++++++++++++++++++++++++++++++++++等额本金+++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++ 通胀率=4*LPR+++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.0475
inflation rate times is 4
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5577.546296296348
total payedback is 3428958.3333333456
total conversion back is: 762237.1675692783
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.005
inflation rate times is 4
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5558.526234567908
total payedback is 3026684.0277777864
total conversion back is: 814889.3600062618
-------------end------------------------
-------------begin----------------------
----------------------------------------
housing loan is 2000000
housing loan payback years 30
payback method is equality_corpus
LPR change forme 0.0475 to 0.08
inflation rate times is 4
-------------result----------------------
0 year 0 month monthly_payback= 13472.222222222223
29 year 11 month monthly_payback= 5592.091049382803
total payedback is 3736579.8611111296
total conversion back is: 741351.5412335462
-------------end------------------------
