From: Jim Lindsey <jlindsey@luc.ac.be> Message-Id: <9801270825.AA13777@alpha.luc.ac.be> Subject: R-beta: "glm" bug continued To: r-help@stat.math.ethz.ch (r-help) Date: Tue, 27 Jan 1998 09:25:56 +0100 (MET) Sorry for the false alarm on the core dump with glm. In fact, my version calculates the AIC. For a saturated model with dispersion parameter, such as the gamma, the dispersion parameter is estimated by the deviance which should be zero. However, it is usually not exactly zero and may be slightly negative. My AIC for the gamma distribution uses lgamma(1/dev) which crashes R. Summary for negative arguments to lgamma: 0 to -176 yields a negative number -177 to -1e5 NA > -1e6 core dump This probably explains a number of my core dumps with nlm using the gamma function in a likelihood function that I mentioned a few weeks ago on this list. nlm can feed very strange values to functions while searching and expects an NA if they are not valid. Jim -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._