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"Chambers" <bdc### [at] yahoo com> wrote:
> The original function is f(x) = M*R*(D^x), where M, R and D are constants.
>
> I'd be using the function g(A) = sum of f(x), where x=0..A
If x is just integers from zero to a, then each term differs by an additional
factor of D. Then you have the sum of a geometric series,
sum_{x=0...A} ( M*R*(D^x) ) = M*R*(1-D^(A+1)) / (1-D).
This looks much nicer on the wikipedia page,
http://en.wikipedia.org/wiki/Geometric_progression . Correct me if I'm
misinterpreting, but this should give you the summation in a single expression.
- Ricky
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