Bill, We already have erf() and erfc() as examples, and help.search() will find them. I've added erfinv() and erfcinv() to the examples and concept index.
I don't see a good reason to add them to e.g. the 'stats' namespace: it is not as if we wish to encourage people to use them instead of [pq]norm. I doubt that those for whom help.search("erf") is too difficult will even manage to find the Wiki (when it is operational). Brian On Mon, 14 Apr 2008, [EMAIL PROTECTED] wrote: > 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 -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ 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.