C＃价值计算与委托人，支付数量，利息

Question

我正在创建付款的自动计算。但我不知道它的公式。单击计算付款按钮后，它将自动计算本金，付款数量和利息，然后在付款时输出。

请参阅屏幕截图

// Example1 Computation
Principal 100000
Number of Payments 9
Interest 2
//Then when the calculate payment is click, execute
Payment 12251.54

// Example2 Computation
Principal 200000
Number of Payments 8
Interest 3.5
//Then when the calculate payment is click, execute
Payment 29095.33

// Example3 Computation
Principal 150000
Number of Payments 12
Interest 1.5
//Then when the calculate payment is click, execute
Payment 13752.00

这是我的字符串

String principal = txt_principal.Text;
String numberofPayments = txt_nop.Text;
String interestRate = txt_irpp.Text;


String payment = txt_payment.Text;

请帮帮我。提前谢谢！

Answer 1

答案在这里：

https://en.wikipedia.org/wiki/Compound_interest

Excel可以为您执行此操作：=PMT(0.02,9,100000)

公式如下：

Where:

PV = 100000 (principal)
RATE = 0.02 (interest)
NPER = 9 (payments)

PMT = -RATE * ( PV * Math.Pow(1+RATE,NPER)) / ((Math.Pow(1+RATE,NPER)-1));

所以对于你的代码：

double PV = double .Parse(txt_principal.Text);
double NPER = double .Parse(txt_nop.Text);
double RATE = double.Parse(txt_irpp.Text) / 100;

double PMT = -RATE * ( PV * Math.Pow(1+RATE,NPER)) / ((Math.Pow(1+RATE,NPER)-1));
txt_payment.Text = (-PMT).ToString();