On Saturday, January 4, 2014 6:43:56 PM UTC+5, Michael Marshall wrote:
@Abraham A.



I had a look at your NPV equation based upon which you have programmed this Excel IRR function http://tadxl.com/excel_irr_function.html , and it all sounds crazy :D



This is what I found on the notes you showed me yesterday at the tad Finance http://thinkanddone.com offices in mid Manhattan



NPV = Sigma [i = 0 to K or Grand Infinity] { PMT_i x PVIFGA ( r%, g%, N or Baby Infinity ) x PVIF( r%, i) }



PVIFGA ( r%, g%, N or Baby Infinity ) = Sigma [j = 0 to N or Baby Infinity] { (1+g%)^j / (1+r%)^(j+1) }



Looking at the NPV formula it sounds as if you have sum of sums of present value of growing annuities where the outer sum goes from zero payments to N payments or upto Grand Infinity payments.



And the inner sum goes from zero periods upto N periods or upto Baby infinity periods.

@Mike

When I took over the job left vacant by late PJ Hooker I found some notes on his desk. The first one on top showed the same NPV formula as you had given yet since it is complicated to write such formula in a text only editor thus a rewrite of Abraham's NPV equation is shown below.

NPV = Sigma [i = 0 to K or Grand Infinity] { PMT_i x PVIFGA ( r%, g%, N or Baby Infinity ) x PVIF( r%, Sigma N-1 ) }

PVIFGA ( r%, g%, N or Baby Infinity ) = Sigma [j = 0 to N or Baby Infinity] { (1+g%)^j / (1+r%)^(j+1) }

The frequencies of payments in PVIFGA formula goes from 0 to N and the sum of all such N-1 terms is then used as a time period to discount the annuity..

Now PJ Hooker did leave us with one of his own Excel add-ins called njsXL add-in for Excel 2007, 2010 and 2013. http://njsxl.njinstruments.com/

njsXL is a collection of 22 statistical functions for Excel yet as PJ wrote in his note that the baton will be passed to Abraham A. to increase the number of these functions to surpass 100 statistical functions hiterto unavailable in native Excel.

The last note from PJ Hooker had a quote from an infamous recent US President who held the High Office from 1993 till 2000. The quote was directed at Abraham A. who thinks he has a chance of making a buck of his online enterprises that sell Excel add-ins such as tadXL, njsXL and others.

"Insanity is doing the same thing over and over again and expecting a different outcome" - Billy Clinton

To honor such a "great" American leader, PJ Hooker programmed an Excel expected value function http://njsxl.njinstruments.com/excel...-function.html

Now Abraham! you take this Excel EV function to confirm the outcome of your hard work.