See the formulas at this site - perhaps you can work with them to get what
you want

http://www.arachnoid.com/lutusp/finance.html#tutorial

"David" wrote:

Hi Duke,

This would work, but I would need a similar formula for the principle amount
and I am tryng to not use an excel function, but the underlying mathimatical
function. Thank you for your thoughts.

--
David


"Duke Carey" wrote:

The total interest paid to maturity would simply be

[pmt amount ] * [# pmts] - [principal amount]


"David" wrote:

Hi Group,

The Cumipmt function returns the cumulative interest paid given a set
interest rate, principle, periods, type and the time period you want to
cover. Does anyone know the algebra behind the function? And I am not realy
interested in "between" periods, but would be happy with the total paid to
maturity date. I was hoping to find a single formula like X= (1+i)^(n-1) or
somthing similar.

Thanks,
--
David