> This is a bug in the mingw runtime, and not in R. So the difference is > between OSes, not between R versions. Note that > > > acosh(2) > [1] 1.316958 > > acosh(2+0i) > [1] 0+NaNi > > acosh(2+1e-10i) > [1] 1.316958+0i > > so it seems to be happening only for exactly real complex numbers. > I think there are also problems with branch cuts. >
Interesting. Unfortunately, that's a common scenerio to convert to complex numbers to ensure complex output if appropriate: acosh(as.complex(-2)) I guess acosh(as.complex(x) + 1e-10i) is a bit better than my current workaround of: myacosh <- function(x) log(x + sqrt(x^2 - 1)) > > On Thu, 30 Nov 2006, [EMAIL PROTECTED] wrote: > > > Full_Name: Tom Short > > Version: 2.4.0 > > OS: Windows XP > > Submission from: (NULL) (68.236.159.227) > > > > > > It looks like there's a bug in acosh with complex number in windows: > > > >> acosh(2) > > [1] 1.316958 > >> acosh(2+0i) > > [1] 0+NaNi > > > > This happens for me on Windows XP with the following versions: > > R version 2.2.0, 2005-10-06, i386-pc-mingw32 > > R version 2.4.0 (2006-10-03) i386-pc-mingw32 > > > > It works fine with the following: > > R version 2.4.0 (2006-10-03) i386-pc-linux-gnu (debian) > > R version 2.1.0, 2005-04-18, i386-pc-linux-gnu (debian) > > > >> acosh(2+0i) > > [1] 1.316958+0i > > > > I didn't find any problem with asinh or atanh taking complex numbers. In > > src/main/complex.c, there are some #ifdef Win32's in z_asin and z_acos, > so it > > may be related to that. > > acosh is unrelated to those. According to this: http://mingw.cvs.sourceforge.net/mingw/runtime/mingwex/complex/cacosh.c?view=markup cacosh uses either casin or cacos, so it looks like they are related. And, the ifdef's for z_acos and z_asin both say "broken for cabs(*z) >= 1", matching this: > acosh(.99+0i) [1] 0+0.1415395i > acosh(1.01+0i) [1] 0+NaNi That also turned up a similar bug in mingw's asinh, this time with real and imaginary components swapped: > asinh(2i) [1] 0+NaNi > asinh(1e-10 + 2i) [1] 1.316958+1.570796i - Tom Tom Short EPRI Solutions, Inc. > > - Tom > > > > Tom Short > > EPRI Solutions, Inc. > > > > ______________________________________________ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > > > -- > 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 > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > -- View this message in context: http://www.nabble.com/bug-in-acosh-%28win32%29-%28PR-9403%29-tf2731987.html#a7670239 Sent from the R devel mailing list archive at Nabble.com. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
