Greetings and Salutations,
The operation that you are using here:
exp(alpha1(0)+beta1(1));
Returns a double instead of an arma::vec. Hence,
from ‘double’ to ‘arma::vec {aka arma::Col<double>}’
To fix this, use:
arma::vec temp(1);
temp << exp(alpha1(0)+beta1(1)); // assumes 1 element in alpha1 and 2
elements in beta1
return temp;
In addition, you should supply a return at the end of the function…
return arma::zeros<arma::vec>(0);
Returns a vector of length 0.
Sincerely,
JJB
From: [email protected]
[mailto:[email protected]] On Behalf Of Amina
Shahzadi
Sent: Sunday, September 11, 2016 10:30 PM
To: [email protected]
Subject: [Rcpp-devel] Error for exp() using RcppArmadillo
Hello Dear
I am new user of RcppArmadillo and Rcpp.
I am using a sample function pasted here. I am haivng error given below: Any
can help in this regard.
In function ‘arma::vec sample(arma::vec, arma::vec)’:
sample.cpp:23:35: error: could not convert
‘exp((alpha1.arma::Col<double>::<anonymous>.arma::Mat<eT>::operator()<double>(0u)
+
beta1.arma::Col<double>::<anonymous>.arma::Mat<eT>::operator()<double>(1u)))’
from ‘double’ to ‘arma::vec {aka arma::Col<double>}’
return exp(alpha1(0)+beta1(1));
^
sample.cpp:34:1: warning: control reaches end of non-void function
[-Wreturn-type]
}
My function sample.cpp is below.
#include <RcppArmadillo.h>
using namespace Rcpp;
using namespace RcppArmadillo;
//[[Rcpp::depends(RcppArmadillo)]]
//[[Rcpp::export]]
arma::vec sample(arma::vec alpha, arma::vec beta)
{
int m = alpha.size();
arma::uvec index(m);
for(int i=0; i<m; i++)
{
index(i) = i;
}
for(int i=0; i<m; i++)
{
for(int j=0; j<m; j++)
{
if(i==j)
{
arma::vec alpha1 =
alpha.elem(find(index !=j));
arma::vec beta1 =
beta.elem(find(index!=j));
return exp(alpha1(0)+beta1(1));
}
else
{
arma::vec alpha2 =
alpha.elem(find(index !=i && index !=j));
arma::vec beta2 = beta.elem(find(index
!=i && index !=j));
return exp(alpha2+beta2);
}
}
}
}
--
Amina Shahzadi
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