#include <boost/geometry.hpp>
#include <boost/geometry/geometries/geometries.hpp>
#include <boost/geometry/multi/geometries/multi_point.hpp>

#define ADD(X,Y) append(poly,make<point_xy<double> >(X,Y))

double poly_area()
{
	using boost::geometry::model::d2::point_xy;
	using boost::geometry::append;
	using boost::geometry::make;

	boost::geometry::model::polygon<point_xy<float> > poly;

	ADD(0.,0.); 
	ADD(1.,0.);
	ADD(0.,1.); 
	ADD(0.,0.);

	return boost::geometry::area(poly);
}

int main()
{
	std::cout << poly_area() << std::endl;
	return 0;
}