Thread: Needing help with C++ programming assignment.

Not looking for you to tell me how to redo the whole thing, just need help pointing out why it dependency keeps dropping.
( Circular PmtCalc.o <- Pmtcalc.cpp dependency dropped. )
It isnt a homework thing its just a in class assignment that has been bugging me because I could not get the result needed.
Do note, I just started my class a week ago, so if the code looks bad do not down it.

Code:

//Monthly Payment on New car


#include <cstdlib>
#include <iostream>
#include <math.h>


using namespace std;


int main()
{
    int num1;
    int num2;
    int num3;
    int num4;


    float math;
    math = pow(1+119,60);


//Down Payment
    num1 = 2200;
//Car Price
    num2 = 22000;
//Monthly interest rate
    num3 = 119;
//Number of Months
    num4 = 60;
    cout<< "Monthly carpayment= " << num3 * (num2 - num1) * ( math/ math -1);


    system("PAUSE");
    return 0;
}

That message you get means you wrote your Makefile incorrectly, not your code.

I was wondering why it was doing that. Now I feel stupid. lol

Any help to why my calculation keeps coming up wrong?

Were you supposed to be paying 11900% interest? If not, maybe you shouldn't use that number.

I was taking it into account, just not really grasped the concept of making it go into programming. The assignment is trying to figure out monthly car payment value, with the car being 22000, down payment 2200, and 5 year at 6.5% apr. The equation he put out to us just threw me off a good bit. I know the outcome outside of the program, just keep messing it up when trying to put it into program.

Oh I changed the number back to original, was throwing out numbers for the first part trying to see why it kept coming out 0. But the previous guy said it was from my PEMDAS problem within the code.

Code is working at the moment, I am having problems trying to do calculations within it. I am trying to come out with the monthly payment of 430.46. I'm confused on how my calculations are not going through right. it always comes back either 0, or 1#inf. Matticus said its my order of operations mess up, but I am clueless on how to put it in to run correctly.

Code:

//Monthly Payment on New car


#include <cstdlib>
#include <iostream>
#include <math.h>


using namespace std;


int main()
{
    int num1;
    int num2;
    double num3;
    int num4;
    int num5;
    double num6;
    
    float math;
    math = pow(1+0.00541666666,60);
    float math2;
    math2 = pow(0.00541666666,60);
//Down Payment
    num1 = 2200;
//Car Price
    num2 = 22000;
//Monthly interest rate
    num3 = 0.00541666666;
//Number of Months all together
    num4 = 60;
// Year
    num5 = 12;
// APR
    num6 = 6.5;
    cout << "Prices on my new car!" << endl;
    cout << "Purchase Price= "<< num2 << endl;
    cout << "Yearly APR=%"<< num6 << endl;
    cout << "Monthly Interest= "<< num6 / num5 << endl;
    cout << "Interest* (purchase-Downpayment)= "<< num3 * (num2 - num1);
    system("PAUSE");
    return 0;
}

The formula goes something like

PMT = (price)(I/12)/(1-(1+I/12)^-60)

Notice you have to do the pow, and then take 1 minus that. Notice also the exponent is negative.

With what you said it came out with a actual price.
cout<< "Monthly carpayment= "<< num3 * (num2 - num1) * ( math/ math -1);
That is the way I attempted to run it. The initial formula on our assignment read like this I(price-downpayment)[(1+I)^60/(1+I)^60-1]
I= Monthly Interest rate

Originally Posted by killeramor

With what you said it came out with a actual price.
cout<< "Monthly carpayment= "<< num3 * (num2 - num1) * ( math/ math -1);
That is the way I attempted to run it. The initial formula on our assignment read like this I(price-downpayment)[(1+I)^60/(1+I)^60-1]
I= Monthly Interest rate

That's algebraically equivalent to the one I gave (relabel I as monthly instead of yearly, then multiply top and bottom by (1+I)^60). Note you still have to put the entire denominator (math-1) in parentheses like so (math/(math-1)).