rss@rss.phtd.tpu.edu.ru
2002-Oct-04 03:57 UTC
Problem with construction (1-x)^(1-y) (PR#2103)
Hello! I have any problem with construction (1-x)^(1-y) if y<1> x=5 > y=.5 > (1-x)^(1-y)[1] NaN> (1-y)[1] 0.5> (1-x)^0.5[1] NaN> (1-x)[1] -4> -4^.5[1] -2 Roma V. Kalaida E-mail rss@rss.phtd.tpu.edu.ru <<insert bug report here>> --please do not edit the information below-- Version: platform = i686-pc-linux-gnu arch = i686 os = linux-gnu system = i686, linux-gnu status = major = 1 minor = 5.1 year = 2002 month = 06 day = 17 language = R Search Path: .GlobalEnv, package:ctest, Autoloads, package:base -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel 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-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
ligges@statistik.uni-dortmund.de
2002-Oct-04 06:20 UTC
Problem with construction (1-x)^(1-y) (PR#2103)
rss@rss.phtd.tpu.edu.ru wrote:> > Hello! > > I have any problem with construction (1-x)^(1-y) if y<1 > > > x=5 > > y=.5 > > (1-x)^(1-y) > [1] NaNWell, that's not a bug! Also for y>=1 (hopefully!): (1-x)^1.1 # NaN You are calculating with real numbers and expecting complex ones! So just try: as.complex(1-x)^(1-y) Uwe Ligges> > (1-y) > [1] 0.5 > > (1-x)^0.5 > [1] NaN > > (1-x) > [1] -4 > > -4^.5 > [1] -2 > > Roma V. Kalaida > E-mail rss@rss.phtd.tpu.edu.ru-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel 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-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
On Fri, 4 Oct 2002 05:57:23 +0200 (MET DST), you wrote:>> (1-x)^0.5 >[1] NaN >> (1-x) >[1] -4 >> -4^.5 >[1] -2As Uwe mentioned, you can't take square roots of negative real numbers, you need to force them to complex first. The reason it worked in the last example is that exponentiation has higher precedence than unary negation, so "-4^.5" is evaluated as "-(4^.5)". Duncan Murdoch -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel 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-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._