on 01/03/2009 02:32 PM rkevinbur...@charter.net wrote: > I had a question about the basic power functions in R. > > For example from the R console I enter: > > -1 ^ 2 [1] -1 > > but also > > -1^3 [1] -1 > > -0.1^2 [1] -0.01 > > Normally pow(-1, 2) return either -Infinity or NaN. Has R taken over > the math functions? If so I would think that -1^2 is 1 not -1 and > -0.1^2 is 0.01 not -0.01. > > Thank you. > > Kevin
Kevin, See R FAQ 7.33 Why are powers of negative numbers wrong? http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-are-powers-of-negative-numbers-wrong_003f For the issue of returning -Inf or NaN, I suspect that you are thinking about negative numbers being raised to non-integer powers. For example, taking into consideration the enlightenment in the above FAQ: > (-1) ^ (1 / 2) [1] NaN > (-2) ^ (1/2) [1] NaN > sqrt(-2) [1] NaN Warning message: In sqrt(-2) : NaNs produced > (-2) ^ 2.5 [1] NaN HTH, Marc Schwartz ______________________________________________ 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.
