You get UB if the first is bigger than the second. Envoyé de mon iPhone
> Le 22 nov. 2014 à 14:30, Søren Højsgaard <sor...@math.aau.dk> a écrit : > > OK; thanks! Shall I read this such as "the behaviour is undefined"? > Søren > > |-----Original Message----- > |From: Romain Francois [mailto:rom...@r-enthusiasts.com] > |Sent: 22. november 2014 13:25 > |To: Søren Højsgaard > |Cc: rcpp-devel@lists.r-forge.r-project.org > |Subject: Re: [Rcpp-devel] sugar: x+y and y+x gives different results when > |there are NA's in y > | > |This has nothing to do with NA. It's just about the size difference. > |sugar does not make attempt at recycling. Your responsibility. > | > |Romain > | > |> Le 22 nov. 2014 à 11:48, Søren Højsgaard <sor...@math.aau.dk> a écrit : > |> > |> Dear all, > |> Came across this: > |> > |> #include <Rcpp.h> > |> using namespace Rcpp; > |> > |> //[[Rcpp::export]] > |> List sumxy(NumericVector x, NumericVector y){ NumericVector xy = > |> x+y; NumericVector yx = y+x; return List::create(xy, yx); } > |> > |> /*** R > |> x <- c(1,3,5,7) > |> y <- c(NA,2,4,6,8) > |> x+y > |> y+x > |> sumxy(x, y) > |> */ > |> > |>> x <- c(1,3,5,7) > |>> y <- c(NA,2,4,6,8) > |>> x+y > |> [1] NA 5 9 13 9 > |>> y+x > |> [1] NA 5 9 13 9 > |>> sumxy(x, y) > |> [[1]] > |> [1] NA 5 9 13 > |> [[2]] > |> [1] NA 5 9 13 8 > |> > |> Is this intentional? Apologies if this has been documented anywhere; > |was unable to find it. > |> > |> Regards > |> Søren > |> > |> > |> _______________________________________________ > |> Rcpp-devel mailing list > |> Rcpp-devel@lists.r-forge.r-project.org > |> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-deve > |> l > _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
