Maybe you have to add #include <stdio.h> #include <R.h> to your C++ source code. Massimiliano Tripoli Il giorno mer, 20/04/2011 alle 22.06 +0200, Sascha Vieweg ha scritto: > #include <iostream> > using namespace std; > void foo (double* x, double* y, double* out) > { > out[0] = x[0] + y[0]; > } > >