Re: [R] Incomplete Gamma Functions and GammaDistribution Doc errata.
My appologies to everyone. Prof. Ripley, please realize that I did not intend to suggest that your mathematics were wrong. My question about mathematical correctness refered to my presention of your formula as an equation. I have great admiration for your work and its influences on my field and, therefore, start with the presumption that all errors must be my own. Mr. Maechler, please understand that I had no intent to insult anyone. I wanted to communicate three things: 1) to point out what I understood to be an error in the documentation (which you both point out to be my own misunderstanding of the terminology). 2) to ask for confirmation that I was interpreting past emails correctly. 3) to argue for an R implementation of an incomplete gamma mathematical function. To the R community, please accept my appologies for a message which you may have taken to be insulting. I am deeply thankful for your work, for your code and for this email list. --adrian __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] Incomplete Gamma Functions and GammaDistribution Doc errata.
Hello all, In the course of trying to implement the CDF of an InverseGammaDistribution, I have run across the need for an igamma() function. Several others have needed this function but the answers I have found so far are not totally clear to me. I'm writing for three reasons: 1) to present a small error in the docs 2) to clarify the approach we are expected to take 3) to request,for the ease of use of myself and others, that the R developers implement igamma(), document the approach they want users to take or do both. 1) An error in the docs of the gamma distribution: - The GammaDistribution(param1,param2) is defined alternatively with two versions of the second parameter which are inverses of one another. 'Rate' arises from one derivation such as that presented in Mathworld: http://mathworld.wolfram.com/GammaDistribution.html (see just below equation (2) ) define $\theta \equiv 1 / \lambda$ to be the time between changes which makes \theta in equation (3) a rate parameter. In the R documentation (i.e. ?pgamma) this same equation is presented but the parameter \theta is now called s and is termed the scale. This goes against general usage of mathworld, wikipaedia, the COLT library, and others who call the s term a rate. Please either change the equation or replace the name with rate and the label with r or nu or theta. 2) Using existing functions to build the igamma(\alpha,\beta): - The incomplete gamma has been mentioned in two previous emails that I could find: http://www.r-project.org/nocvs/mail/r-help/2000/1006.html and http://www.r-project.org/nocvs/mail/r-help/2000/3618.html both of which suggest that the upper incomplete gamma can be obtained using the pgamma() function. Is Prof. Ripley's message (the first above) saying that upperIncompletegamma(x,\rate) = pgamma(x,\rate) * gamma(\rate) ? I have not yet been able to see why this would be true. I keep tripping myself up on the differing notation of R, mathworld, wikipaedia and Abramowitz and Stegun's Handbook of mathematical functions. Would someone please confirm that this is mathematically correct? 3) Adding an igamma() function or documentation for how to generate it. Since I am at least the third person not clever enough to see the way to derive the igamma directly, because the lack of an igamma() function has cost me a chunk of my day, because using functions related to distributions to derive pure mathematical functions is counter intuitive, and because two implementations already exist, I hope the R developers would be willing to incorporate an igamma() function directly into R. The implementation could either use the code posted to the list: http://www.r-project.org/nocvs/mail/r-help/1998/0295.html or be a convinience function around the pgamma and gamma solution suggested in the emails presented above. Alternatively, if this approach doesn't suit you, would someone please add an explanation to the documentation for the gamma function explaining how to generate an igamma(\alpha, \beta) using the current functions? Thanks to all, adrian __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] How to plot a blank plot
Hello everyone, In plotting several graphics, I'd like to be able to plot a blank plot as in: par(mfrow=c(2,1)) plot(BLANK) hist(rgamma(10,6463.7,scale=0.015471),xlim=c(0,120),main=Emergence) I realize screen allows me to do this, but I figure the functionality must be there. Is there an equivalent to plot(BLANK)? thanks, adrian PS. please reply direct as I'm not subscribed to the list. __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
RE: [R] How to plot a blank plot
No, the opposite. plot.new() will allow me to plot again in the same location. I want to skip the current location and plot on the next (bottom) split. I want my plots on the bottom half of the page so the top half can have my notes. --adrian On Fri, 2004-02-13 at 12:21, Liaw, Andy wrote: Is plot.new() what you're looking for? Andy From: Adrian Custer Hello everyone, In plotting several graphics, I'd like to be able to plot a blank plot as in: par(mfrow=c(2,1)) plot(BLANK) hist(rgamma(10,6463.7,scale=0.015471),xlim=c(0,120),main= Emergence) I realize screen allows me to do this, but I figure the functionality must be there. Is there an equivalent to plot(BLANK)? thanks, adrian PS. please reply direct as I'm not subscribed to the list. __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html -- Notice: This e-mail message, together with any attachments, contains information of Merck Co., Inc. (One Merck Drive, Whitehouse Station, New Jersey, USA 08889), and/or its affiliates (which may be known outside the United States as Merck Frosst, Merck Sharp Dohme or MSD and in Japan, as Banyu) that may be confidential, proprietary copyrighted and/or legally privileged. It is intended solely for the use of the individual or entity named on this message. If you are not the intended recipient, and have received this message in error, please notify us immediately by reply e-mail and then delete it from your system. -- __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
