Compilation Error using RcppArmadillo package in R with rowvec - rcpp

Question

I am trying to compile the following code. Please see below what I have tried so far. Is there anything that I am missing. Any help would be appreciated.
#include <RcppArmadillo.h>
// [[Rcpp::depends(RcppArmadillo)]]
using namespace Rcpp;
// [[Rcpp::export]]
List beta(const arma::rowvec beta,
const int n,
const int L1,
const int p,
const arma::mat YWeight1,
const arma::mat z){
double S0=0;
for(int i = 0;i < n; ++i){
arma::rowvec zr = z.rows(i,i);
S0 += exp(arma::as_scalar(beta*zr.t()));
}
List res;
res["1"] = S0;
return(res);
}
I can't copy the error but this is what I am getting.
no match for call to '(Rcpp::traits::input_parameter<const arma::Row<double>
and so on...

Answer 1

There is a rowvec converter. The issue here is:
filece5923f317b2.cpp:39:34: error: type 'Rcpp::traits::input_parameter::type' (aka 'ConstInputParameter >') does not provide a call operator
rcpp_result_gen = Rcpp::wrap(beta(beta, n, L1, p, YWeight1, z));
Few thoughts: 1. There is already a function called beta() and 2. there is a variable named beta that might be causing havoc with Rcpp attributes.
Solution:
Remove the using namespace Rcpp;
Rename the function away from beta() to beta_estimator().
Specify the length of Rcpp::List
Access by numeric index instead of string.
Corrected code:
#include <RcppArmadillo.h>
// [[Rcpp::depends(RcppArmadillo)]]
// [[Rcpp::export]]
Rcpp::List beta_estimator( // renamed function
const arma::rowvec beta,
const int n,
const int L1,
const int p,
const arma::mat YWeight1,
const arma::mat z){
double S0 = 0;
for(int i = 0;i < n; ++i){
arma::rowvec zr = z.rows(i,i);
S0 += exp(arma::as_scalar(beta*zr.t()));
}
// Specify list length
Rcpp::List res(1);
res[0] = S0;
return(res);
}