[Rcpp-devel] variable affectation in Rcpp Rcpp Armadillo

[Nicolas Heslot]

Hi,

Thank you for your quick answer.
Sorry that I did not explain well enought my issue.
I did not know about cppbugs but I just checked and it does not seem that I
can use it for my model because it lacks some of the distribution I need.
The fraction of code could seems obscure but it is just the updating for a
block of parameters in the model.
My problem is rather simple I think.
Once I affect a matrix to a variable I can't manage to overwrite the content
of that variable with a different matrix. I really can't figure out how to
do it.

Nicolas

On Wed, Jun 15, 2011 at 7:52 PM, Dirk Eddelbuettel <edd at debian.org> wrote:

>
> Salut Nicolas,
>
> On 15 June 2011 at 17:03, Nicolas Heslot wrote:
> | Hi rcpp-devel!
> | First of all thank you for this awesome tool!
>
> Pleasure, and welcome.
>
> | I started a few days ago coding with Rcpp to try to reduce the computing
> time
> | of a MCMC model.
> | However, I don't have experience with C/C++ and I can't figure out how to
> | reaffect a new content to a variable.
> | This seems probably very simple to you but I can't figure it out, and
> this is
> | the last step preventing my code to work out I think...
> | The objects all_ui, all_ui2, all_ui3, all_rd and all_corMat are list
> objects
> | containing matrix
> | But once a matrice extracted from one of those lists is affected, to let
> say
> | the object ui I can't affect the next matrix to ui at the next iteration.
> | I tried to find a way to eliminate the object at each iteration or to
> empty it
> | using .reset but without success.
> |
> | So any help would be very much appreciated!
> | (fragment of code posted below)
> |
> | arma::mat tmp;
> | arma::mat tmp2;
> | arma::mat tmp3;
> | arma::mat ui;
> | arma::mat ui2;
> | arma::mat ui3;
> | arma::mat sigma;
> |
> | for (int j = 0; j < P-1; j++) {
> | tmp2.fill(0);
> | tmp3.fill(0);
> |  for (int i = 0; i < N-1; i++) {
> |  ui = all_ui[i];
> | ui2 = all_ui2[i];
> |  ui3 = all_ui3[i];
> | rdi = all_rd[i];
> | all_corMati = all_corMat[i];
> |  sigma = sigma2*all_corMat[i];
> | // calculate mean and variance
> | arma::mat tmp = (solve(sig%all_corMat[i])* gen_a(i,j))*all_ui[i];
> | arma::mat tmp2 += (all_rd[i] -
> mu*trans(all_ui3[i])-(X(i)*alpha)*trans(all_ui2
> | [i]) + gen_a(i,j)*a.row(j)*trans(all_ui[i]))*tmp;
> | arma::mat tmp3 += (gen_a(i,j)*trans(all_ui[i]))*tmp;
> | }
> | }
> |
> | Thank you for your help
>
> I'm with Whit here and confess that I do not know your question is. If you
> show us what you tried, what you expected to happen and what actually
> happened we may help.
>
> (By the way, there is no tax on indentation in code and it does make it
> more
> readable for those of us who didn't write it ;-)
>
> Dirk
>
> | It probably does not help much
> | but I use R2.13 with the last version of the packages on a windows XP
> plateform
> |
> | Nicolas
> |
> |
> | ----------------------------------------------------------------------
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> | Rcpp-devel at lists.r-forge.r-project.org
> | https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
>
> --
> Gauss once played himself in a zero-sum game and won $50.
>                      -- #11 at http://www.gaussfacts.com
>
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