//------------------------------------------------------------------------
//  Programming Assignment #1
//  
//  Written by C A Thomas
//  September 2008
//
//  Purpose:  To compute the monthly payment of an installment loan and 
//            the balance remaining after half of the installments have 
//            been made. Also, compute the total amount of interest paid
//            over the life of the loan.
//-----------------------------------------------------------------------

//------------------ Proprocessor Section -------------------------------

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

//----------------- Main Function ---------------------------------------

int main ()
{

//---------------- Variables and Constants ------------------------------    
  
  int
     numofpay,		// number of monthly payments
     k;                 // half the number of payments

  float
     i, 		// annual interest rate
     loanam,		// amount of loan
     payment,    	// monthly payment
     totalip,		// total interest paid
     temp,              // part of payment processing
     balance;		// balance half way through

//----------------- Input Phase -----------------------------------------

  cout << "\n\n  Welcome to the Loan Analysis Program!" ;
 
  cout << "\n\n    Enter loan amount:        " ;
  cin >> loanam;
  cout << "\n    Enter annual interest rate (as a decimal):    " ;
  cin >> i;
  cout << "\n    Enter number of monthly payments:     " ;
  cin >> numofpay;

//---------------- Processing Phase -------------------------------------

  temp = (1 + (i / 12));

  k = numofpay / 2;

  payment = (pow(temp,numofpay)) / (pow(temp,numofpay) -1) * loanam * (i / 12);

  balance = payment * ((1 - pow(temp,(k-numofpay))) / (i / 12));

  totalip = payment*numofpay-loanam;
  
//--------------- Output Phase -----------------------------------------

 cout << fixed << setprecision(2);   // force fixed point format for floats 

 cout << "\n\n ~~~~~~~~~~~ Loan Summary~~~~~~~~~~~\n  " ;

 cout << "\n         Annual Interest Rate:       % " << i*100;
 cout << "\n         Number of Monthly Payments:   " << numofpay << endl; 
 cout << "\n         Loan Amount:                $ " << setw(10) << loanam;
 cout << "\n         Monthly payment:            $ " << setw(10) << payment;
 cout << "\n         Balance halfway through:    $ " << setw(10) << balance;
 cout << "\n         Total interest paid:        $ " << setw(10) << totalip << endl;

 return 0;

}