While loop for loan repayment?

In the picture shown, I have to basically create each loan payment table underneath its respective black line. Although I was able to create the first two tables, I am having trouble with two things: The first is finding the "Sum of Interest Paid" and "Sum of Payments" at the bottom of each table; the second problem is actually creating the third table. Any assistance would be appreciated. Here is my code:

 InitialBalance = input('Enter the initial balance in US$ : '); % 10,000,3000,9000
% if initial balance is more than or equal to 5000, then interest rate is
% 2%. Anything else is 1%
if InitialBalance>=5000 
    rate=0.02;
    fprintf('\nYour minimum monthly payment is $%g\n',rate*InitialBalance+1)
    Minimum=rate*InitialBalance+1;
else
    rate=0.01;
    fprintf('\nYour minimum monthly payment is $%g\n',rate*InitialBalance+1)
    Minimum=rate*InitialBalance+1;
end

 MonthPay = input('Enter the Monthly Payment in US$ : '); % 12000, 4000, 2000

 month=0; % initialize months
Payment=0; % initialize payment
Interest=0;
fprintf('\nMonths \t Interest($) \t Payment($) Balance($)\n')
fprintf('  %2i          %2i           %2i        %2i\n',month,Interest,Payment,InitialBalance)
Balance=InitialBalance; 

 while MonthPay>=Minimum % initiates while loop if and only if monthly payment >= minimum payment
    while Balance~=0
        month=month+1; 
        Payment=MonthPay;
        Interest=rate*Balance;
        Payment=Interest+Balance;
        if Balance-Payment<0
            Balance=0;
        else
            Balance=Balance-Payment;
        end
        fprintf('  %2i          %2i           %2i     %2i\n',month,Interest,Payment,Balance)
    end
end

 fprintf('\nSum of Interest Paid = $%b\n')
 fprintf('\tSum of Payments = $%b')

Answer 1

[Image Analyst]

Your final two fprintf()'s don't have any numerical values to be put into the %b. You need to have a variable sumOfPayments and sumOfInterest and increment that inside the loop by the payment and interest for that iteration, after you've initialized it to zero before the loop of course.

And I wouldn't use %i and %b. b is not even anything. I would use %d for integers and %.2 for fractional real numbers.

[Karan Sandhu]

I'm sorry sir but I don't understand what you mean by "variable sumOfPaymens and increment that inside the loop". Also, what about my second question?

[Image Analyst]

Try this:

InitialBalance = input('Enter the initial balance in US$ : '); % 10,000,3000,9000
% if initial balance is more than or equal to 5000, then interest rate is
% 2%. Anything else is 1%
if InitialBalance>=5000
  rate=0.02;
  fprintf('\nYour minimum monthly payment is $%g\n',rate*InitialBalance+1)
  Minimum=rate*InitialBalance+1;
else
  rate=0.01;
  fprintf('\nYour minimum monthly payment is $%g\n',rate*InitialBalance+1)
  Minimum=rate*InitialBalance+1;
end

MonthPay = input('Enter the Monthly Payment in US$ : '); % 12000, 4000, 2000

theMonth=0; % initialize months
Payment=0; % initialize payment
Interest=0;
fprintf('\nMonths \t Interest($) \t Payment($) Balance($)\n')
fprintf('  %2d %11.2f %15.2f %11.2f\n',theMonth,Interest,Payment,InitialBalance)
Balance=InitialBalance;
loopCounter = 1;
sumOfPayments = 0;
sumOfInterest = 0;
maxIterations = 20;
% initiates while loop if and only if monthly payment >= minimum payment
while MonthPay >= Minimum && Balance~=0 && loopCounter <= maxIterations
  theMonth = theMonth + 1;
  Payment = MonthPay;
  Interest = rate*Balance;
  
  % Get the sum of these so far.
  sumOfPayments = sumOfPayments + MonthPay;
  sumOfInterest = sumOfInterest + Interest;
  
  Balance = Interest + Balance;
  if Balance-Payment<0
    Balance = 0;
  else
    Balance = Balance-Payment;
  end
  fprintf('  %2d %11.2f %15.2f %11.2f\n',...
    theMonth, Interest, Payment, Balance)
  loopCounter = loopCounter + 1;
end

fprintf('\nSum of Interest Paid = $%.2f\n', sumOfInterest)
fprintf('\tSum of Payments = $%.2f\n', sumOfPayments)

[Karan Sandhu]

I love you, Image Analyst.