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;
}