server/a.cpp

#include <complex>
#include "point.h"

	double make_arg(const point &pt,const point &p)
	{
		return  std::arg(std::complex<double>(pt.x,pt.y)-std::complex<double>(p.x,p.y));
	}

int main()
{
    printf("00 --- 10 %f\n",make_arg(point(1,0),point(0,0)));
    printf("00 --- 01 %f\n",make_arg(point(0,1),point(0,0)));
    printf("00 --- -10 %f\n",make_arg(point(-1,0),point(0,0)));
    printf("00 --- 0-1 %f\n",make_arg(point(0,-1),point(0,0)));
}