C++ within R: HELP with error for function in C++ (within R):

expected primary-expression before ',' token for the line

beta[,i]=arma::inv(X.t()*X+lambda[i]*arma::eye(2,2))*X.t()*Y[,i];

and points to the comma in beta and then also points to the comma in Y. Both were declared (as you can see below) as matrices (one inside and the other passed as parameter).

Code below:

arma::mat col_ridge_2(arma::mat Y, arma::mat X, arma::vec lambda) {

int n = Y.n_cols; arma::mat beta(2,100); //set stop condition for lambda being length of n here int i;

for (i=0;i<100;i++) {

beta[,i]=arma::inv(X.t()*X+lambda[i]*arma::eye(2,2))*X.t()*Y[,i];

} return beta;

}