[Rcpp-devel] clarification of interaction between RInside and RcppEigen

[Stephen J. Barr]

Thanks for the pointer to sugar.

I was just trying to think of a simple example. So my C++ code will be
essentially:

int main() {

    RInside R(argc, argv);          // create an embedded R instance
    R.parseEval("X = generateSomeMatrix()");

    Eigen::MatrixXd Xeigen;

    // this is the part that I am still a bit unclear of:
    // use Rcpp::as to make Xeigen take the value of X

}

On Tue, Aug 7, 2012 at 2:34 PM, Dirk Eddelbuettel <edd at debian.org> wrote:

>
> Also note that "just" getting random numbers is taken care of via Rcpp
> sugar
> which wraps rnorm() etc:
>
> R> library(inline)
> R>
> R> R> f <- cxxfunction(signature(), plugin="Rcpp", body='
> +    Rcpp::RNGScope tmp;
> +    return rnorm(3);
> + ')
> R>
> R> set.seed(42)
> R> rnorm(3)                         ## using R
> [1]  1.370958 -0.564698  0.363128
> R> set.seed(42)
> R> f()                              ## using the Rcpp function just created
> [1]  1.370958 -0.564698  0.363128
> R>
>
> Same RNG draws, as we deal properly with the RNG state (where RNGScope
> helps).  Look at the list archives, this has been discussed a few times if
> it seems too "magic".
>
> Dirk
>
>
>
> --
> Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com
>
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