On Wed, 29 Mar 2006, Robin Hankin wrote: > Hi guys > > perhaps my original message wasn't so clear. > > My point was that the documentation is inconsistent with the > function.
I think it is _your reading_ of the documentation that is inconsistent. An equally plausible reading is that both x and y must be numeric or complex. > How to remedy this? > > (i) add a line to Trig.Rd along the lines of "atan2() will not work > if the first argument > is real and the second argument complex" > > or > (ii) Modify atan2() so that it coerces the first argument to a > complex if necessary. > > > I'd prefer option (ii) but can't see a quick fix. Really? It's a one-line change. BTW, this *really* is an R-devel topic, so please try to use the appropriate list. Suggestions for changes to R get lost in the torrent of R-help extremely easily. And only the designers can say 'but atan2 wasn't originally designed for complex arguments.' but the code suggests otherwise. > > > rksh > > > > > On 28 Mar 2006, at 19:52, Jeff Newmiller wrote: > >> Robin Hankin wrote: >>> Hi >>> >>> ?atan2 says that atan2(y,x)=atan(y/x) for x and y numeric or complex >>> vectors. >>> >>> Well, I would expect atan2(1,1i) to be equal to atan(-1i), but >>> >>>> atan2(1,1i) >>> Error in atan2(y, x) : Non-numeric argument to mathematical function >> >> Ravi Varadhan pointed out that you need to make both arguments complex >> to address the error message you obtained... but atan2 wasn't >> originally >> designed for complex arguments. I suspect that what you really want is >> to use the Arg function: >> >>> Arg(1/1i) >> [1] -1.570796 >> >> -- > > > -- > Robin Hankin > Uncertainty Analyst > National Oceanography Centre, Southampton > European Way, Southampton SO14 3ZH, UK > tel 023-8059-7743 > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > -- 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 ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
