Re: [R] calculating IRR (accounting) in R

From: McGehee, Robert <Robert.McGehee_at_geodecapital.com>
Date: Thu 01 Dec 2005 - 08:44:36 EST


Hello,
If we define IRR implicitly such that NPV(C, IRR) = 0, then we can just write an IRR function that finds the zeros of the NPV function. Here are two such functions:

NPV <- function(C, r) {

    sum(C / (1 + r) ^ (seq(along = C) - 1))
}

IRR <- function(C) {

    uniroot(NPV, c(0, 1), C = C)$root
}

Hope this helps,
Robert

-----Original Message-----
From: paul sorenson [mailto:sourceforge@metrak.com] Sent: Wednesday, November 30, 2005 3:50 PM To: r-help
Subject: [R] calculating IRR (accounting) in R

I am trying to replace a spreadsheet model of a project justification with an R script.

I can't seem to track down R functions to calculate Internal Rate of Return and NPV? Am I missing something? NPV doesn't seem so difficult to calculate (at least for a regular series) but I am struggling to identify how to solve for IRR in R.

It would be sufficient if it worked for a regular series but really useful if there was something that worked with irregular time series.

cheers



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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Dec 01 08:51:18 2005

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