生成摊销计划

最近我第一次买房子的时候,我写了一个javascript应用程序供我个人使用。

下面是我用来确定每月付款的代码片段:

var balance = 200000; // for example
var periods = 360; // 30 years
var monthlyRate = (0.065)/12;  // 0.065= APR of 6.5% as decimal
var monthyPayment = (monthlyRate /(1-(Math.pow((1+monthlyRate),-(periods)))))*balance;

for (var i=0; i<360; i++) {
  var interestForMonth = balance * monthlyRate;
  var principalForMonth = monthlyPayment - interestForMonth;
  balance -= monthlyPayment; // probably should be -= principalForMonth see comments below
  // output as necessary.
}

之后很容易做一个摊销表。(正如其他人提到的,请注意舍入错误,我在实现中没有充分处理这个问题。)

有很多网站提供这些公式。一个在下面: http://www.math4finance.com/financial-formulas.php

不需要复杂的算法,因为公式通常很简单。

布赖恩是对的。公式很简单。

如果您希望您的解决方案是一个好的解决方案,您将注意舍入错误。如果您只是让舍入错误累积和传播,那么您可以在计划结束时舍入几美分。通过仔细的编程,您可以将错误最小化。

此外,如果您的计算机上有MS Excel,您可以从MS Office Online下载摊销模板。

var annuity =  P * (i + i / (Math.pow(1+i,n) -1));

//P: principal, I: periodic interest rate, N: number of periods

C中的摊销计划公式#

            numerator = i * principle * (Math.Pow(1 + i, n));
            denominator = (Math.Pow(1 + i, n) - 1);

            /* Calculation of Amortization Payment Amount  */
            payment = numerator / denominator;

这就是我最终创造的。我已经发布了整个测试程序。它是用RPG编写的,但对于任何其他语言都应该很容易理解。

 H ActGrp(*caller) BndDir('MODULES') DftActGrp(*no)
   //*********************************************************************
   // Program . . . . . AMORT
   //*********************************************************************
   // Printer/Display Files
 FAMORTDF   CF   E             WORKSTN sfile(SFL01:rrn01)
   //*********************************************************************
   // Named Constants
  /copy modules/qcopysrc,statuscopy

   // Named Indicators
 D indicatorPtr    S               *   Inz(%Addr(*IN))
 D                 DS                  Based(IndicatorPtr)
  /copy modules/qcopysrc,scrncopy

   // Subfile  Fields
 D rrn01           S              4P 0 inz(0)

   //*********************************************************************
   // Misc Fields
 D* Monthly Payment
 D m               S             12P 2        
 D* Principal
 D p               S             12P 2                                      
 D* Interest
 D i               S              5P 3                                      
 D* Length (in Years)
 D l               S              3P 0                                      
 D* Monthly Interest
 D j               S             10P10                                      
 D* # of Months
 D n               S              5P 0                                      
 D* Current Monthly Int.
 D h               S             12P 2                                      
 D* Current Principal
 D c               S             12P 2                                      
 D* New Balance
 D q               S             12P 2                                      

   //*********************************************************************
   // External Program Procedures

   // Internal Subprocedures
 D Init            PR
 D Main            PR
 D SubfileFilled   PR              N
 D ClearScreen     PR
 D IsValidData     PR              N
 D LoanPayment     PR            12P 2
 D  principal                    12P 2
 D  interest                      5P 3
 D  loanPeriod                    3P 0
 D  paymentsYear                  3P 0

   // External Subprocedures
   ///copy modules/qsrvsrc,p.string

   //*********************************************************************
   // Entry Parms
 D AMORT           PR                  extpgm('AMORT')
 D AMORT           PI
   //*********************************************************************
  /free
   Init();
   Main();

   *inlr = *on;
  /end-free

 P*--------------------------------------------------
 P* Procedure name: Init
 P* Purpose:
 P* Returns:
 P*--------------------------------------------------
 P Init            B
 D Init            PI

  /free

   pgm = 'AMORT';
   sflDsp = *off;

   return;

  /end-free
 P Init            E


 P*--------------------------------------------------
 P* Procedure name: Main
 P* Purpose:
 P* Returns:
 P*--------------------------------------------------
 P Main            B
 D Main            PI

  /free

   dow (not F3) and (not F12);

     write OVR01;
     exfmt CTL01;
     ClearScreen();

     if (IsValidData()) and (not F3) and (not F12);

       // Fill the header information
       dPayment = LoanPayment(dLoanAmt:dIntRate:dLoanPrd:dPayYear);
       dNumPaymnt = dLoanPrd * dPayYear;
       m = dPayment + dExtraPay;
       p = dLoanAmt;
       q = p;

       // Fill the table
       if (SubfileFilled());
         sflDsp = *on;
       endif;
     endif;

   enddo;

   return;

  /end-free
 P Main            E


 P*--------------------------------------------------
 P* Procedure name: SubfileFilled
 P* Purpose: Fill the subfile
 P* Returns:
 P*--------------------------------------------------
 P SubfileFilled   B
 D SubfileFilled   PI              N

 D isFilled        S               N
 D x               S              4P 0
 D intCume         S             12P 2
 D extraPayCume    S             12P 2
 D payDate         S               D
 D payment         S             12P 2
 D extraPayment    S             12P 2

  /free

   isFilled = *on;

   sflClear = *on;
   write CTL01;
   sflClear = *off;
   rrn01 = 0;
   x = 0;

   // Setup the work fields
   payment = dPayment;
   extraPayment = dExtraPay;
   payDate = dStartDate;

   // Create records until there is a zero balance
   dow (q > 0);

     x += 1;
     eval(h) h = p * j; // Monthly Interest

     // Adjust for final payment
     if (p < m);
       m = p + h;
       payment = p;
       extraPayment = h;
     endif;

     // Calulate Principal
     c = m - h;
     // Calulate the new balance
     q = p - c;

     // Accumulate the interest and extra payments
     intCume += h;
     extraPayCume += extraPayment;

     // Determine the next pay date
     select;
       when dTerms = '1'; //Yearly
         payDate += %years(1);
       when dTerms = '2'; //Semi-Annual
         payDate += %months(6);
       when dTerms = '3'; //Quarterly
         payDate += %months(3);
       when dTerms = '4'; //Monthly
         payDate += %months(1);
       when dTerms = '5'; //Bi-Weekly
         payDate += %days(14);
     endsl;

     // Fill the subfile
     sPayNum = x;
     sPayDate = payDate;
     sBegBal = p;
     sSchedPay = payment;
     sExtraPay = extraPayment;
     sTotPay = m;
     sInterest = h;
     sPrincipal = c;
     sEndBal = q;
     sCumeInt = intCume;

     // Move the End balance to the beginning balance
     p = q;

     rrn01 += 1;
     write SFL01;

   enddo;

   // Return the calculated information to the header
   dActPaymnt = x;
   dTotInt = intCume;
   dTotEPay = extraPayCume;

   if (rrn01 < 1);
     isFilled = *off;
   endif;

   return isFilled;

  /end-free
 P SubfileFilled   E


 P*--------------------------------------------------
 P* Procedure name: ClearScreen
 P* Purpose:
 P* Returns:
 P*--------------------------------------------------
 P ClearScreen     B
 D ClearScreen     PI

  /free

   c = 0;
   h = 0;
   i = 0;
   j = 0;
   l = 0;
   m = 0;
   n = 0;
   p = 0;
   q = 0;
   dPayment = 0;
   dNumPaymnt = 0;
   dActPaymnt = 0;
   dTotEPay = 0;
   dTotInt = 0;

   return;

  /end-free
 P ClearScreen     E


 P*--------------------------------------------------
 P* Procedure name: IsValidData
 P* Purpose: Validate the data on the screen
 P* Returns: True or False
 P*--------------------------------------------------
 P IsValidData     B
 D IsValidData     PI              N

 D isValid         S               N

  /free

   if (dLoanAmt <> 0) and (dIntRate <> 0) and (dLoanPrd <> 0) and
      (dPayYear <> 0) and (dStartDate <> %date('0001-01-01'));
     isValid = *on;
   else;
     isValid = *off;
   endif;

   return isValid;

  /end-free
 P IsValidData     E


 P*--------------------------------------------------
 P* Procedure name: LoanPayment
 P* Purpose: Calculates the payment
 P* Returns:
 P*--------------------------------------------------
 P LoanPayment     B
 D LoanPayment     PI            12P 2
 D  principal                    12P 2
 D  interest                      5P 3
 D  loanPeriod                    3P 0
 D  paymentsYear                  3P 0

 D retMonthlyPayment...
 D                 S             12P 2

  /free

   eval(h) n = loanPeriod * paymentsYear;
   eval(h) j = interest / (paymentsYear * 100);

   eval(h) m = principal * (j / (1 - (1 + j) ** -n));

   return m;

  /end-free
 P LoanPayment     E

此代码已通过我们的贷款计算器进行了测试。如果测试与Excel相比,20万美元的贷款减少了约32美分。我相信这对解决问题是有帮助的。