Thread: calcuations

ok i got the pow formula to work. KNow my issues is with my AmountIntrest .

Code:

AmountInterest = a  * (1 + i/12);

Here you are applying a years worth of interest each month. You read in an annual interest rate. As was done in the formula I provided, you have to adjust that for just one month.
so would that mean ti would have to write it as

Code:

 AmountInterest = ( pow(1 + i / 12,  n)*a;

This way it si deviding the months by the interest the * by the currentanount ler me knwo if you want to see the rest of the program.

Originally Posted by redmondtab

ok i got the pow formula to work. KNow my issues is with my AmountIntrest .

Code:

AmountInterest = a  * (1 + i/12);

Here you are applying a years worth of interest each month. You read in an annual interest rate. As was done in the formula I provided, you have to adjust that for just one month.
so would that mean ti would have to write it as

Code:

 AmountInterest = ( pow(1 + i / 12,  n)*a;

This way it si deviding the months by the interest the * by the currentanount ler me knwo if you want to see the rest of the program.

.
I don't think you need to be using the pow function at all for this bit. The monthly interest would be the amount outstanding times the interest rate divided by 12.

So that seems to be simply:- a*i/12. (a =ammount outstanding)
(Of course I am assuming that the interest rate is defined as "the interest rate which can be applied monthly to pay off the loan ).

yeah i finally under stand that know. I was trying to take it from a % to a demical. Which i did not need to do. Go figure. THanks for the help on this one

Originally Posted by dwks

I think your logic in simplifing the formula is flawed, but I can't prove it.

Code:

( pow(1 + i / 12,  n) * (i / 12 * a) ) /  (pow(1 + i / 12,  n) – 1 )

No it doesn't, unless you meant (5*5*5*5)/(5*5*5) = 5.

Yes that is what I mean't maybe I should have put:-

5*5*5*5
-----------
5*5*5


Which was what I was thinking.

Originally Posted by dwks

I think your logic in simplifing the formula is flawed, but I can't prove it.

Code:

( pow(1 + i / 12,  n) * (i / 12 * a) ) /  (pow(1 + i / 12,  n) – 1 )

Refering to that bit, the quoted formula above is not the formula I simplified, I simplified
the formula he mistakenly originally used. :-
( pow(1 + i / 12, n) * (i / 12 * a) ) / (pow(1 + i / 12, n – 1 ))

The formula you quoted cannot be simplified, or at least no one has managed it yet
(and I am sure many eminent mathemeticains have tried!!)

ok i need my teach is dead set that is is correct. Can some one pleae run this and tell me if the get teh correct answers

Code:

/*************************************************************  
File Name:     Tmitchellwk1
Description:   Display Loan Amortization Schedule
Date:          August 28th, 2006
Designer;      Tabatha Mitchell
Assignment:    week1
Functions:      None
**************************************************************/
#include <stdio.h>
#include <math.h>


/*Program to compute Amortization Schedule*/

main  ()
{
   
  
   int   TermLoan,  // length of the loan
         PaymentNumber,  //number of payments made
          Numberofmonths, //Number of months in the loan
          count,
          n,c; //Letters used for the calculations
double   AmountPrinciple, //Amount paid on principle
         AmountInterest,  //amount paid to interest
         LoanBlance, //amount owed on loan\ count,
         CurrentBlance,
          LoanAmount, //amount of the loan  
         InterestRate, //interest rate on loan
           a,i,
           NewBlance, //amount of new amount owed
           PaymentAmount;  //amount paid to loan       
       
 //start of main program
   printf ("Please enter in loan amount, Term of Loan in months and Interest Rate.\n");
  
 
        while (scanf("%lf%d%lf", &LoanAmount, &TermLoan, &InterestRate) != 3
                     || (LoanAmount < 0 || TermLoan < 0 || InterestRate < 0 ))
          {
             while ((c = getchar()) != '\n' && c != EOF);
             printf ("Please re-enter in loan amount, Term of Loan in months and Interest Rate.\n"); 
         }         
   CurrentBlance = LoanAmount;
   Numberofmonths = TermLoan; 
     i = InterestRate;
               n = Numberofmonths;
               a = CurrentBlance;
                PaymentNumber = 0;
                count = 0;  
   
                
printf ("\amortization Schedule\n");
printf ("_____________________\n");

          
        PaymentAmount = pow((1+i/12),n)*(i/12*a)/pow((1+i/12),n)-1;        
   
            while(PaymentNumber < Numberofmonths)
           {   
              //[ (1 + i / 12) ** n * (i / 12 * a) ] / [ (1 + i / 12) ** n – 1 ]
                    
           PaymentNumber++; //Start number of months for amortization schedule
           count++;
           AmountInterest = a  * (i/12);  
           AmountPrinciple = PaymentAmount - AmountInterest;
           LoanBlance = a -AmountPrinciple;
           printf ("CurrentBlance %.2f\n", a);
           printf ("InterestRate %.2f\n", i);
          printf ("PaymentNumber %d\n",  PaymentNumber);
          printf ("LoanBlance  %.2f\n", LoanBlance);
          printf ("PaymentAmount %.2f\n", PaymentAmount);
          printf ("AmountPrinciple %.2f\n", AmountPrinciple);
          printf  ("AmountInterest %.2f\n", AmountInterest);
          printf ("_______________________\n\n");
          a = LoanBlance;  
                }//end of while loop 

getchar ();
getchar ();
printf ("hit enter to end");
return 0;         
}

Dose the math work for you. I'm getting wrong number but was told that this is how the calcualtions should be?