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Mortgage Homework

10 replies on 1 page. Most recent reply: Dec 11, 2009 6:16 AM by George B

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Agustin Nazario

Posts: 2
Nickname: anaza201
Registered: Feb, 2008

Mortgage Homework

Posted: Feb 23, 2008 10:18 AM

I will begin by saying that I have zero programming experience but I have to take this class as part of the degree requirements. Bellow is a problem that I've been working on for several days now.

The monthly payment on mortgage loan of L dollars, at a rate of interest r is given
by
Monthly payment = [L(r/12) ]/[ - 1]
Where N is the number of years of mortgage. Write a program to find the monthly
payment for 30 years, for principals from $100,000 through $200,000(with increments
of $20,000) and interest rates of 6% through 10% (with increments of 0.5%). Print
monthly payment as a whole number (rounded off).
The output must be a neat table, similar to the following (your answers may be slightly
different because of rounding off).
Principal 6% 6.5% 7% 7.5% 8% 8.5% 9% 9.5% 10%
100000 600 632 665 699 733 768 804 840 877
120000 719 758 798 839 880 922 965 1009 1053
140000 … … … … … … … … …
160000 … … … … … … … … …
180000 … … … … … … … … …
200000 … … … … … … … … …
Hint: Use the following idea to compute
double temp = 1+r/12;
double temp1 = 1;
for (int i = 1; i<=12*N;i++)
{
temp1 = temp1*temp;
}
The final formula now becomes:
double mp = (L*(r/12)*temp1)/(temp1-1);

I don't expect people to do my homework, but I'm stuck and any help will be appreciated.
This is what I have so far and obviously is not working. Thanks in advance

public class Mortgage
{
public static void main(String args[])
{
int L;
for(L=100000;L<=200000;L+=20000)
{
double r;
for(r=6.0;r<=10.0;r+=0.5)

{
int N = 30;
double temp=1+r/12;
double temp1=1;
for(int i=1;1<=12*N;i++)
{
temp1=temp1*temp;
}
double mp=(L*(r/12)*temp1)/(temp1-1);
System.out.println(mp);

}
}
}
}

George B

Posts: 24
Nickname: hmgeorge
Registered: Feb, 2008

Re: Mortgage Homework

Posted: Feb 24, 2008 8:35 AM

The first problem is a typo that's causing an infinite loop. The typo is fixed in the reformatted code below, with the problem line commented out:

public class Mortgage {
    public static void main(String args[]) {
        int L;
 
        for (L = 100000; L <= 200000; L += 20000) {
            double r;
 
            for(r = 6.0; r <= 10.0; r += 0.5) {
                int N = 30;
                double temp  = 1 + r / 12;
                double temp1 = 1;
 
////            for (int i = 1; 1 <= 12 * N; i++) {
                for (int i = 1; i <= 12 * N; i++) {
                    temp1 = temp1 * temp;
                }
 
                double mp = (L * (r / 12) * temp1) / (temp1 - 1);
                System.out.println(mp);
            }
        }
    }
}

Hopefully this can help get you unstuck. Note that if you enclose code snippets between 'java' and '/java', replacing the single quotes with square brackets, formatting will be preserved in your postings to this forum.

Agustin Nazario

Posts: 2
Nickname: anaza201
Registered: Feb, 2008

Re: Mortgage Homework

Posted: Feb 24, 2008 10:54 AM

Your help really pointed me in the right direction.
Thank you.

Les H

Posts: 6
Nickname: crazyman65
Registered: Dec, 2009

Re: Mortgage Homework

Posted: Dec 10, 2009 10:36 AM

This program has been bugging me for days and started searching for help today and came across your site. I have a couple of problems that i just can't figure out.
One is how to make the output in to a table format as asked in the directions the other is when I run the code my answers are like the first one 50000 when it should be 500.
Can somebody point me in the correct direction.
Thanks

Les


class mortgage {
public static void main (String[] args)
{
   int L;
   for (L=100000; L<=200000; L+=20000){
         double r;
         for(r=6; r<=10; r+.5){
              int N=30;
              double temp = 1+r/12;
              double temp1 = 1;
       
              for(int i = 1; i<=12*N; i++){
                   temp1=temp1*temp;
              }
              double mp = (L * (r / 12) * temp1) / (temp1-1);
                 System.out.println("Principal \t 6%\t 6.5%\t 7%\t 7.5%\t 8% \t8.5% \t9% \t 9.5% \t 10%");
                 System.out.println("100,000 \n 120,000 \n 140,000 \n 160,000 \n 180,000 \n 200,000");
                 System.out.print("\t");
                 System.out.printf("$%1.0f\n",mp);
          }
     }
  }
}

Les H

Posts: 6
Nickname: crazyman65
Registered: Dec, 2009

Re: Mortgage Homework

Posted: Dec 10, 2009 10:56 AM

I figured out my math problem I still need help on figuring out how to do a table out put as stated in the orignal program.
Here is my corrected code.

Les

import static void java.lang.System.out;
class mortgage {
public static void main (String[] args)
{
int L;
for (L=100000; L<=200000; L+=20000){
     double r;
     for(r=6; r<=10; r+.5){
         int N=30;
         double temp = 1+r/12;
         double temp1 = 1;
 
         for(int i = 1; i<=12*N; i++){
         temp1=temp1*temp;
         }
          double mp = (L * (r / 12) * temp1) / (temp1-1);
          out.println("Principal \t 6%\t 6.5%\t 7%\t 7.5%\t 8% \t8.5% \t9% \t 9.5% \t 10%");
          out.println("100,000 \n 120,000 \n 140,000 \n 160,000 \n 180,000 \n 200,000");
          out.print("\t");
          out.printf("$%1.0f\n",mp);
         }
      }
   }
}

Les H

Posts: 6
Nickname: crazyman65
Registered: Dec, 2009

Re: Mortgage Homework

Posted: Dec 10, 2009 10:59 AM

I figured out my math problem I still need help on figuring out how to do a table out put as stated in the orignal program.
Here is my corrected code.

Les

class mortgage {
public static void main (String[] args)
{
int L;
for (L=100000; L<=200000; L+=20000){
     double r;
     for(r=.06; r<=.10; r+.005){
         int N=30;
         double temp = 1+r/12;
         double temp1 = 1;
 
         for(int i = 1; i<=12*N; i++){
         temp1=temp1*temp;
         }
          double mp = (L * (r / 12) * temp1) / (temp1-1);
          System.out.println("Principal \t 6%\t 6.5%\t 7%\t 7.5%\t 8% \t8.5% \t9% \t 9.5% \t 10%");
          System.out.println("100,000 \n 120,000 \n 140,000 \n 160,000 \n 180,000 \n 200,000");
          System.out.print("\t");
          System.out.printf("$%1.0f\n",mp);
         }
      }
   }
}

George B

Posts: 24
Nickname: hmgeorge
Registered: Feb, 2008

Re: Mortgage Homework

Posted: Dec 10, 2009 11:51 AM

I'm not sure what you're trying to accomplish with some of the math using temp and temp1 and N, but this will print your results as a table.

class mortgage {
    public static void main (String[] args) {
        int principal;
        double rate;
 
        //
        // print table header
        //
        System.out.print("Principal \t");
        for (rate = .06; rate <= .10; rate += .005) {
            System.out.printf("%.1f\t", rate * 100);
        }
        System.out.println("");
 
        //
        // calculate and print table body
        //
        for (principal = 100000; principal <= 200000; principal += 20000) {
            System.out.print("" + principal + "    \t");
 
            for (rate = .06; rate <= .10; rate += .005) {
                int N = 30;
                double temp = 1 + rate/12;
                double temp1 = 1;
 
                for (int i = 1; i <= 12 * N; i++) {
                    temp1 = temp1 * temp;
                }
                double mp = (principal * (rate / 12) * temp1) / (temp1-1);
                System.out.printf("$%1.0f\t", mp);
            }
            System.out.print("\n");
        }
    }
}

Les H

Posts: 6
Nickname: crazyman65
Registered: Dec, 2009

Re: Mortgage Homework

Posted: Dec 10, 2009 2:19 PM

George B,
Thank you so very much.
Now I realized I still messed up on the math.
I need it to show out to 10% and i currently only make it to 9.5.
Any ideas???

Thanks
Les

Les H

Posts: 6
Nickname: crazyman65
Registered: Dec, 2009

Re: Mortgage Homework

Posted: Dec 10, 2009 3:52 PM

I figured it out.

Les H

Posts: 6
Nickname: crazyman65
Registered: Dec, 2009

Re: Mortgage Homework

Posted: Dec 10, 2009 6:52 PM

Here is what I get when I run the code:
--------------------Configuration: <Default>--------------------
Principal 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
$100000 $600 $632 $665 $699 $734 $769 $805 $841 $878
$120000 $719 $758 $798 $839 $881 $923 $966 $1009 $1053
$140000 $839 $885 $931 $979 $1027 $1076 $1126 $1177 $1229

What I need to figure out is to have it show this:
--------------------Configuration: <Default>--------------------
Principal 6.0% 6.5% 7.0% 7.5% 8.0% 8.5% 9.0% 9.5% 10.0%
$100000 $600 $632 $665 $699 $734 $769 $805 $841 $878
$120000 $719 $758 $798 $839 $881 $923 $966 $1009 $1053
$140000 $839 $885 $931 $979 $1027 $1076 $1126 $1177 $1229

I thought I could add another % in the second print line it compiles ok but when I run the code it errors out.
Any ideas??

George B

Posts: 24
Nickname: hmgeorge
Registered: Feb, 2008

Re: Mortgage Homework

Posted: Dec 11, 2009 6:16 AM

In a printf statement, a percent sign is used to mark the beginning of a placeholder that indicates how a value is to be formatted, e.g. "%d" means it should be formatted as a decimal number or "%f" means it should be a floating point number. If you just put in a "%", the library errors out because it finds a tab ("\t") as the next character and it doesn't know how to format "%\t". To insert a percent sign use "%%".

You can see all (well, most anyway) of the formatting options on the api page for the java Formatter class: http://java.sun.com/j2se/1.5.0/docs/api/java/util/Formatter.html

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