That's not a bad idea. If the wiki comes up again, please do it. They are so short I wonder that they just can't go in to base R though. It's not particularly matlab terminology, it's engineering and physics terminology pretty widely. See, e.g. Abramowitz and Stegun.
For specifcity, here are the four I would suggest. erf <- function (x) 2 * pnorm(x * sqrt(2)) - 1 erfc <- function (x) 2 * pnorm(x * sqrt(2), lower = FALSE) erfinv <- function (x) qnorm((1 + x)/2)/sqrt(2) erfcinv <- function (x) qnorm(x/2, lower = FALSE)/sqrt(2) But I don't feel strongly enough about it to push it on R-devel myself right now. I always forget the connexion and it seems to come up when you least expect it. I've just added them to my little horde of useful stuff, so I'm OK now! Bill. Bill Venables CSIRO Laboratories PO Box 120, Cleveland, 4163 AUSTRALIA Office Phone (email preferred): +61 7 3826 7251 Fax (if absolutely necessary): +61 7 3826 7304 Mobile: +61 4 8819 4402 Home Phone: +61 7 3286 7700 mailto:[EMAIL PROTECTED] http://www.cmis.csiro.au/bill.venables/ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ben Bolker Sent: Monday, 14 April 2008 11:00 AM To: [EMAIL PROTECTED] Subject: Re: [R] R equivalent of erfcinv in matlab <Bill.Venables <at> csiro.au> writes: > > At a guess ... > > > erfc <- function(x) 2 * pnorm(x * sqrt(2), lower = FALSE) > > erfcinv <- function(x) qnorm(x/2, lower = FALSE)/sqrt(2) > > erfc(0.3) > [1] 0.6713732 > > erfcinv(erfc(0.3)) > [1] 0.3 > > > > It may not hurt to include these wrappers in R for matlab refugees. > They seem to be coming thick and fast these days. > There's a page on the wiki about matlab to R (actually I think it's titled "Octave to R" -- this could go on there whether or not it gets into base R. I would put it on myself, right now, but the wiki appears to be down? ping wiki.r-project.org PING econum.umh.ac.be (193.190.194.5) 56(84) bytes of data. Ben Bolker ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
