/* -*-ePiX-*- */
#include "epix.h"
using namespace ePiX;

const P sz(3.5,3);
const P O(0,0);
const double shrink(0.2);

void sidearrow(const P& tail, const P& head)
{
  P tmp(head - tail);
  tmp *= 1.0;
  P shift(-pt_to_screen(8)/norm(tmp)*J(tmp));
  arrow(tail + shrink*tmp + shift, head - shrink*tmp + shift);
}

int main()
{
  picture(P(0,0), sz, "1.05 x 0.9in");

  begin();

  P e3(1.5,0), e2(0,2.5), e1(sz);

  const P dx(-2,-4);

  arrow_inset(0.25);

  line(e1, e2);
  line(e2, e3);
  line(e3, e1);

  sidearrow(e1, e2);
  sidearrow(e2, e3);
  sidearrow(e3, e1);

  label(e1, P(4,0), "$e_1$", r);
  label(e2, P(-4,0), "$e_2$", l);
  label(e3, P(0,-4), "$e_3$", b);

  ddot(P(e3.x1(),1.75), P(4,0), "$z_0$", r);

  tikz_format();
  end();
}