cube sum test example

test.cpp

#include <RcppArmadillo.h>
// [[Rcpp::depends(RcppArmadillo)]]

// [[Rcpp::export]]
arma::mat cube_sum1(arma::cube c) {
        arma::mat ss(c.n_cols, c.n_slices, arma::fill::zeros);
        for(int i = 0; i < c.n_rows; i++) {
                ss += c.tube(arma::span(i), arma::span::all);
        }
        return ss;
}

// [[Rcpp::export]]
arma::mat cube_sum2(arma::cube c) {
        arma::mat ss(c.n_cols, c.n_slices, arma::fill::zeros);
        for(int i = 0; i < c.n_rows; i++) {
        for(int j = 0; j < c.n_cols; j++) {
        for(int k = 0; k < c.n_slices; k++) {
                ss(j,k) += c(i,j,k);
        }}}
        return ss;
}

/*** R

c <- array(runif(96*21*1),c(96,21,1))
print(cube_sum1(c))
print(cube_sum2(c))
*/

test.R

# run as R -d valgrind -f test.R

library(Rcpp)
sourceCpp("test.cpp")