Rcpp function crashes

My problem: I am using R.3.0.1 together with RStudio 0.97.551 on a 64bit Windows7 PC and I have begun to outsource a function to C/C++ using Rcpp. The function compiles, but evaluating it within an R function produces a runtime error. I am not able to find out why and how to fix this. Details Below is my cpp-file... let's say it's called "vector.cpp" ``` #include <Rcpp.h> using namespace Rcpp; // [[Rcpp::export]] NumericVector l5(double z, double k, double s, double K, double theta, double x, double h, NumericVector m){ int n = m.size(); NumericVector a(n); NumericVector bu(n); NumericVector b(n); NumericVector c(n); for(int i=0; i<n+1; i++){ a[i] = pow(z,m[i]) * (pow((x*pow(h,m[i])/K), theta) - 1) * (K/theta); for (int j=0; j<i; j++){ bu[i] += pow(z,j) * (1 - z) * fmax(((pow((s/K), theta) - 1) * (K/theta)), ((pow((x*pow(h, j)/K), theta) - 1) * (K/theta))); } b[i] = k *bu[i]; c[i] = k * pow(z, m[i]) * fmax(((pow((s/K), theta) - 1) * (K/theta)), ((pow((x*pow(h, m[i])/K), theta) - 1) * (K/theta))); } return wrap(a-b-c); } ``` which I compile in R (or RStudio) using the command ``` sourceCpp(<path to file>/vector.cpp) ``` It compiles - so far so good. However, when I go on to use the function l5 within other R functions it often leads R to crash (both in RStudio and the plain R GUI). In fact, also evaluating it itself isn't any more stable. To reproduce this, e.g. try evaluating l6 multiple times ``` l6 <- function(zs, ks, ss, Ks, thetas, xs, hs){ z=zs k=ks s=ss K=Ks theta=thetas x=xs h=hs m=0:30 res <- l5(z, k, s, K, theta,x, h, m) return(res) } ``` and run ``` l6(0.9, 0.1, 67, 40, 0.5, 44, 1.06) ``` Specifically, it produces the following runtime error ``` This application has requested Runtime to terminate it in an unusual way. ``` So what is wrong with my function? Solution As Dirk suggested below there is an elementary mistake in the for loop, where i runs from 0 to n and thus has n+1 elements, but I intialized only vectors of length n. To avoid this mistake I now implemented the function using iterators ``` #include <Rcpp.h> using namespace Rcpp; // [[Rcpp::export]] NumericVector l5(double z, double k, double s, double K, double theta, double x, double h, NumericVector m){ int n = m.size(); NumericVector a(n); NumericVector bu(n); NumericVector b(n); NumericVector c(n); for(NumericVector::iterator i = m.begin(); i != m.end(); ++i){ a[*i] = pow(z, m[*i]) * (pow((x*pow(h, m[*i])/K), theta) - 1) * (K/theta); for(int j=0; j<*i; j++){ bu[*i] += pow(z,j) * (1 - z) * fmax(((pow((s/K), theta) - 1) * (K/theta)), ((pow((x*pow(h, j)/K), theta) - 1) * (K/theta))); } b[*i] = k *bu[*i]; c[*i] = k * pow(z, m[*i]) * fmax(((pow((s/K), theta) - 1) * (K/theta)), ((pow((x*pow(h, m[*i])/K), theta) - 1) * (K/theta))); } return wrap(a-b-c); } ``` Many thanks again!