Hi All I cannot build the following sample using accumulators. Do you know why? I used times ago an example and it worked without any problem. Can you help me with that? I have the following error error: ‘covariate1’ was not declared in this scope #include <iostream> #include <boost/accumulators/accumulators.hpp> #include <boost/accumulators/statistics/stats.hpp> #include <boost/accumulators/statistics/mean.hpp> #include <boost/accumulators/statistics/moment.hpp> #include <boost/accumulators/statistics/variance.hpp> #include <boost/accumulators/statistics/covariance.hpp> using namespace boost::accumulators; int main() { accumulator_set<double, stats<tag::mean, tag::variance, tag::covariance<double, tag::covariate1> > > x_acc; x_acc( 1.1, covariate1 = 2.2 ) ; return 0; }