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- Path: opalo.etsiig.uniovi.es!lozano
- From: lozano@opalo.etsiig.uniovi.es (Lozano Mosterin, Jesus)
- Newsgroups: comp.lang.ada,comp.lang.basic.misc,comp.lang.c,comp.lang.c++,comp.lang.clipper,comp.lang.pascal.delphi.misc
- Subject: Re: IRR formula - Please help me
- Message-ID: <1996Feb24.123032.6860@opalo.etsiig.uniovi.es>
- Date: 24 Feb 96 12:30:32 +0100
- References: <312EAB76.5463@pixie.co.za>
- Organization: Universidad de Oviedo
-
- Hi, Maurizio
-
- > I need to implemet the IRR formula (and calculation) into
- > a system under development.
- > I don't have a clue on what is (or looks like) the IRR.
- > Please, help me.
-
- In short, IRR=Internal Rate of Return
-
- NetPresentValue = -Inversion(time0) + SUM from t=m to t=N
- OF net_incomes/(1+rate_of_required_return)^t
- (note that t could be non integer refered to rate periodicity)
-
- You can calculate it on a hand calculator or a
- spreadsheet (@IRR) BUT (!) take on account
- - Some packages are considering that the inversion was
- realized on time=1 NOT time=0, and the NPV,IRR results changes!
- - IRR<>rate_of_required_return, but IRR its derivated
- from supposing NetPresentValue=0, and calculating this rate.
- - There are no exact computation to do this, and that
- tools uses and heuristic o aprox. calculation, usually asking you
- an initial value to search :-(
- -There are some cases (many cases) in wich the calculus
- has NO or VARIOUS solutions (related with the switch of
- net_incomes signs over the time periods)
-
- Resuming, the IRR could be a bad practice to evaluate bussines
- projects, especially comparing it with other methods like the calculus
- of the net present value on a range of required rates or math programing
- on cash flows or option's theory or... The IRR is mostly (well?) used
- in banking operations, evaluating underlayed rates on multi transactions
- (like more than one investment).
- I'll post you ASAP one or two algorithms to iterate in
- the heuristic calculus. They are from me, so be warned about
- checking the results. I think they are quite precises, but they
- had no consideration on the multiples rates problem.
- Best regards
-
- STD Disclaim: I speak from my own opinions. I usually change my
- wrong opinions. My employer it's an organization so it don't speak
- about this or another topic. It could has a PERFECT opinion, but
- it's quite reserved on telling us. As an reasonable and intelligent
- counterpart you could extract valid or invalid propositions from
- this mail, so you are only receiving unverified data for your
- future work on the topic, and that includes an active evaluation.
-