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foo_par.cpp
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foo_par.cpp
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// [[Rcpp::depends(RcppParallel)]]
#include <RcppParallel.h>
#include <Rcpp.h>
using namespace RcppParallel;
struct Sum : public Worker
{
// source vector
const RVector<double> input;
// accumulated value
double value;
// constructors
Sum(const Rcpp::NumericVector input) : input(input), value(0) {}
Sum(const Sum& sum, Split) : input(sum.input), value(0) {}
// accumulate just the element of the range I've been asked to
void operator()(std::size_t begin, std::size_t end) {
value += std::accumulate(input.begin() + begin, input.begin() + end, 0.0);
}
// join my value with that of another Sum
void join(const Sum& rhs) {
value += rhs.value;
}
};
using namespace RcppParallel;
// [[Rcpp::export]]
double parallelVectorSum(Rcpp::NumericVector x) {
// declare the SumBody instance
Sum sum(x);
// call parallel_reduce to start the work
parallelReduce(0, x.length(), sum);
// return the computed sum
return sum.value;
}