Rcpp example functions using attributes

RcppAttributes.cpp

#include <Rcpp.h>

using namespace Rcpp;

// [[Rcpp::export]]
int fibonacciCpp(const int x) {
     
     if (x == 0) return(0);
     if (x == 1) return(1);
     
     return (fibonacciCpp(x - 1)) + fibonacciCpp(x - 2);
}

// [[Rcpp::export]]
NumericVector convolveCpp(NumericVector a, NumericVector b) {
    
    int na = a.size(), nb = b.size();
    int nab = na + nb - 1;
    NumericVector xab(nab);
    
    for (int i = 0; i < na; i++)
        for (int j = 0; j < nb; j++)
            xab[i + j] += a[i] * b[j];
    
    return xab;
}

// [[Rcpp::export]]
List lapplyCpp(List input, Function f) {
    
    List output(input.size());
    
    std::transform(input.begin(), input.end(), output.begin(), f);
    output.names() = input.names();

    return output;
}