Monthly payment algorithm

[DerPflug]

I'm trying to get a monthly payment algorithm to work but I seem to be messing up with the order of precedence or something. I'm not sure. The algorithm is:

(P * R * (1 + R)^L)/((1 + R)^L - 1)

P = principal = $1000
R = interest rate = %10
L = length of loan = 12 months

With these values the monthly payment should be 87.92.

I currently have:
payment = (P * R * pow(1 + R,L))/(pow(1 + R,L) - 1);
but this doesn't seem to work. Any ideas?

 

[apatterno]

Are you sure your expected result is right?

On my calculator I got 146.76.


[sub]I REALLY hope that helps.[/sub]
Will

 

[DerPflug]

I just realized what I was doing wrong. The Rate needs to be divided by twelve before its inserted into the equation.