HI Dirk, hi Romain, allright, this is now clear to me, if I want to reuse memory, the allocated memory from R (so implicitly in C) must of course have the same type - otherwise the memory has a different size.
On the other side I then assume, that the Rcpp:as<class M>() function makes a cast and therefore creates a copy with new allocated memory of the type included in M? Therefore a reuse of memory with this function is not possible. Best Simon On Jun 6, 2013, at 8:31 PM, Dirk Eddelbuettel <e...@debian.org> wrote: > > On 6 June 2013 at 13:17, Dirk Eddelbuettel wrote: > | > | On 6 June 2013 at 19:05, Simon Zehnder wrote: > | | sorry I had overseen this message from you. Okay, so the explicit cast to > SEXP together with the assignment operator makes the deal. But it still > includes the reuse of memory right, i.e. the '=' does not call the copy > constructor? > | > | But how could an _unsigned int_ from Armadillo possibly have the same value > | as a _signed int_ in R? > | > | Either you are efficient (no copy), or you are correct (with a copy). I do > | not see how you could have both. > > Sorry -- please ignore this message. > > I had mistakenly assumed that you were still thinking about arma::umat to > integer. For direct int-to-int this is indeed efficient just like the > double-to-double is for arma::mat to NumericMatrix (and dito for vectors). I > though that was a given -- maybe need to make this (even) more explicit in > the documentation. > > So in sum: you get correct and efficient behaviour if and only if you stick > with the types natively supported in Armadillo and R. > > Dirk > > -- > Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com _______________________________________________ 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
