# Need Help With Equation in Java

• 02-08-2013, 03:32 AM
Alsark
Need Help With Equation in Java
I just started Java and this is probably a dumb question. I am trying to put the following equation into Java:

http://i224.photobucket.com/albums/d...vaEquation.png

In Java I typed the following (this is just a test program, my actual one has commenting/prompts):

final double FACTOR = -1/30;
double b = 0.0;
double n = 0.0;
double p = 0.0;
double dailyInterest = 0.0;
double apr = 0.0;

apr = kb.nextDouble();

b = kb.nextDouble();

p = kb.nextDouble();

dailyInterest = apr/365;

n = FACTOR*((Math.log(1+(b/p)*(1-(Math.pow(1+dailyInterest,30)))/Math.log(1+dailyInterest))));

I've tried to break it apart a few different ways and as separate variables to clean it up, but the answer I get is always "NaN" for my n value (the values I am trying to use are 13.65 for apr, 2013 for b, and 25 for p; test values provided by the professor).

Any ideas on why this would be occurring?
• 02-08-2013, 03:59 AM
lenois
Re: Need Help With Equation in Java
check the value of Factor, I didn't have time to compile and test it out, but if what you wrote is exactly what you had, you may have a data type issue.

so put this somewhere:

System.out.println(FACTOR);

edit I imagine you know what i am pointing out since all of your other values are properly initialized.
• 02-12-2013, 02:50 AM
Alsark
Re: Need Help With Equation in Java
Quote:

Originally Posted by lenois
check the value of Factor, I didn't have time to compile and test it out, but if what you wrote is exactly what you had, you may have a data type issue.

so put this somewhere:

System.out.println(FACTOR);

edit I imagine you know what i am pointing out since all of your other values are properly initialized.

It looked like FACTOR as a fraction as outputting zero; however, even changing that to a decimal of -.013333333333, the output of my equation is still NaN...
• 02-12-2013, 07:44 AM
JosAH
Re: Need Help With Equation in Java
If 'apr' is 'annual percentage' then i= (apr/365)/100;

kind regards,

Jos
• 02-12-2013, 05:04 PM
Alsark
Re: Need Help With Equation in Java
Quote:

Originally Posted by JosAH
If 'apr' is 'annual percentage' then i= (apr/365)/100;

kind regards,

Jos

Thank you! I did (apr/100)/365 and it seems that the equation is working now!