Calculating Interest Payments

[David Dickinson]

InitialSum * InterestRate * 1.0 / (1.0 - Math.pow(1.0 + InterestRate,-1.0 * 12));

Hi folks,

The above code is supposedly capable of working out monthly interest charges. I have done my own calculation using "my" understanding of how to calculate interest and the two values differ.

I'm fairly sure this is calculating compound interest, but im still uncertain as to why the calculation is adding 1.0 to the interest rate and minusing 1.0 from the number of payments?

([B]1.0 +[/B] InterestRate,[B]-1.0 * 12[/B]));

Any ideas?

[Junilu Lacar]

The expression (-1.0 * 12) actually multiplies 12 by negative 1.0 which in your context results in a negative exponent

[David Dickinson]

Thanks for that.

So why you want to multiply the interest (plus 1 for some strange reason) by -12?