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

const double ht(-0.375);
const double wd(sqrt(1.5));
const double x0(wd*sqrt(1.0/3)); // critical point

double g(double x)
{
  return -0.35*x*(wd-x)*(wd+x);
}

double f(double x)
{
  return g(x) + ht;
}

int main()
{
  picture(P(-1.5,-1), P(1.5,1), "2.4 x 1.25in");

  begin();
  bold();
  P O(0,0);

  line(P(xmin(),0), P(xmax(),0));
  line(P(0,ymin()), P(0,ymax()));

  masklabel(P(0,ymin()), P(0,0), "$q\\leqq -2l\\sqrt{l}$", t);

  set_crop();
  plot(f, xmin(), xmax()-0.15, 60);
  marker(P(x0, f(x0)), TIMES);
  marker(P(-x0, f(-x0)), TIMES);

  label(O, P(-2,-2), "$O$", bl);
  label(P(xmax(),0), P(0,-2), "$X$", b);
  label(P(0,ymax()), P(2, 0), "$Y$", r);

  label(P(0,ymin()), P(0,-6), "\\textsc{Fig.~19}", b);

  tikz_format();

  end();
}