Gamma funtion(s) bug
On 30-Mar-09 20:37:51, Duncan Murdoch wrote:
On 3/30/2009 2:55 PM, (Ted Harding) wrote:
On 30-Mar-09 18:40:03, Kjetil Halvorsen wrote:
With R 2.8.1 on ubuntu I get:
gamma(-1)
[1] NaN Warning message: In gamma(-1) : NaNs produced
lgamma(-1)
[1] Inf Warning message: value out of range in 'lgamma' Is'nt the first one right, and the second one (lgamma) should also be NaN? Kjetil
That is surely correct! Since lim[x->(-1)+] gamma(x) = +Inf, while lim[x->(-1)-] gamma(x) = -Inf, at gamma(-1) one cannot choose between +Inf and -Inf, so surely is is NaN.
But lgamma(x) is log(abs(gamma(x))), so it looks okay to me. Duncan Murdoch
Oops, yes! That's what comes of talking off the top of my head (I don't think I've ever had occasion to evaluate lgamma(x) for negative x, so never consciously checked in ?lgamma). Thanks, Duncan! Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 30-Mar-09 Time: 22:28:52 ------------------------------ XFMail ------------------------------