On 17 August 2010 09:20, Romain Francois <rom...@r-enthusiasts.com> wrote: > Le 17/08/10 07:43, baptiste auguie a écrit : >> >> Hi, >> >> On 17 August 2010 03:24, Dirk Eddelbuettel<e...@debian.org> wrote: >>> >>> On 16 August 2010 at 19:43, Dirk Eddelbuettel wrote: >> >> [...] >> >>> The only trouble is that nobody has written the corresponding 'glue' code >>> to >>> make >>> >>> arma::cx_vec a1(y1.begin(), y1.size(), false); >>> >>> happen: create an Armadillo complex vector from an Rcpp::ComplexVector. >>> We >>> can init by scalar size, what you'd need to insert for now is a simply >>> (and >>> very pedestrian) copy-loop. >> >> I'm confused, isn't >> >> arma::cx_colvec a1 = Rcpp::as< arma::cx_vec>( y1 ); >> >> aimed at doing this kind of conversion? (that's what I use, following >> Romain's tip) >> >> baptiste > > I don't think you are confused. This works well, but it does require some > extra copying, which Dirk was trying to spare. > > Using the "advanced" constructor in armadillo means that both the > ComplexVector and the cx_vec use the same memory. although it says loud and > clear in armadillo documentation : > > """ > This is faster, but can be dangerous unless you know what you're doing! > """
Thanks. Two questions then, 1- reinterpret_cast< std::complex<double>* > seems like a good option, does it work with real / complex matrices as well? The only things that came up from googling it were related to RcppGSL, not RcppArmadillo. 2- when is it not safe? ;) Thanks! baptiste PS: i wouldn't want to hijack the original query; I'll open a new thread if this seems to raise further questions. _______________________________________________ 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
