On 16 August 2010 at 19:43, Dirk Eddelbuettel wrote:
| Hi Christian,
|
| Thanks for your interest in Rcpp, and for posting here.
|
| On 16 August 2010 at 17:19, Christian Gunning wrote:
| | Dear list,
| |
| | I'm trying to use the ComplexVector class, and I'm having difficulty
| | with multiplication. I sugar multiplication, element-by-element
| | multiplication (no * operator for either), and using temporary
| | Rcomplex variables (don't really understand what I'm doing here).
|
| Well, NumericVector et al aren't really made for all possible math ops done
| on vectors, real or complex. They are first and foremost storage types. But
| for the math we do have Armadillo and RcppArmadillo. So in the short run, I
| would suggest the following two-step procedure:
|
| i) have a good look at Armadillo (http://arma.sf.net) and use the cx_mat
| or cx_vec types for mulitplication; write a small test program to see
| that everything works
|
| ii) use RcppArmadillo to from R via Rcpp / RcppArmadillo to this
| functionality
|
| | I was able to successfully import get("*") as an Rcpp::Function and do
| | the multiplication through R. Is this the best option for now?
|
| I am sure we can do better than this but I am not sure all pieces are in
| place just yet.
Looks like I wasn't all that far off. This builds:
library(inline)
code <- '
ComplexVector y1(i), y2(ii);
//arma::cx_vec a1(y1.begin(), y1.size(), false);
//arma::cx_vec a2(y2.begin(), y2.size(), false);
arma::cx_vec a1(y1.size());
arma::cx_vec a2(y2.size());
arma::cx_vec a3 = a1 * a2;
arma::cx_vec a4 = a1 + a2;
List z = List::create(a1, a2, a3, a4);
return z;
'
fun <- cxxfunction(signature(i="compex", ii="comples"), code,
plugin="RcppArmadillo")
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.
Hth, Dirk
|
| Cheers, Dirk
|
|
| | Thanks,
| | Christian Gunning
| | University of New Mexico
| |
| | // doesn't work
| | SEXP rcpp_hello_world(SEXP i, SEXP ii){
| | using namespace Rcpp ;
| |
| | ComplexVector y1(i), y2(ii);
| | int n(y1.size()), j;
| | ComplexVector y3(n), y4(n);
| | y3 = y1 * y2; // no operator
| | for (j = 0; j++; j<n) {
| | y4[j] = y1[j] + y2[j]; // no operator
| | }
| | List z = List::create( y1, y2, y3) ;
| | return z ;
| | }
| |
| | // does work, doing multiplication in R
| | SEXP mymult(SEXP input1, SEXP input2) {
| | Rcpp::Environment base("package:base");
| | Rcpp::Function funbase = base["get"];
| | SEXP funbase1 = funbase("*");
| | Rcpp::Function funmult(funbase1);
| | Rcpp::ComplexVector xxa = funmult(input1, input2);
| | return xxa;
| | }
| |
| | SEXP rcpp_hello_world(SEXP i, SEXP ii){
| | using namespace Rcpp ;
| | ComplexVector y3( mymult(i, ii) );
| | return y3 ;
| | }
| | _______________________________________________
| | 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
|
| --
| 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
--
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
