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

P f1p(double t)
{
  return P(cosh(t), sinh(t));
}

P f1m(double t)
{
  return P(-cosh(t), sinh(t));
}

P f2p(double t)
{
  return P(sinh(t), cosh(t));
}

P f2m(double t)
{
  return P(sinh(t), -cosh(t));
}

double MAX(2.25), sc(0.95), Rad(3);

int main()
{
  picture(P(-4,-4), P(4,4), "4 x 4in");

  begin();
  arrow_init();
  degrees();
  bold();
  P pB(sc*MAX, sc*MAX), pD(-sc*MAX, -sc*MAX), O(0,0);
  P pA(-sc*MAX, sc*MAX), pC(sc*MAX, -sc*MAX);

  double th(20), t0(atanh(Tan(th)));

  P pa1(f1p(0)), pa2(f1p(t0)), pb1(f2p(0)), pb2(f2p(t0));

  clip_box(P(-MAX,-MAX,-1), P(MAX,MAX,1));
  plot(f1p, -3, 3, 40);
  plot(f1m, -3, 3, 40);

  plot(f2p, -3, 3, 40);
  plot(f2m, -3, 3, 40);
  clip_box();

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

  line(pA, pC);
  line(pB, pD);

  label(pA, P(-2, 2), "$A$", tl);
  label(pC, P( 2,-2), "$C$", br);

  label(pB, P( 2, 2), "$B$", tr);
  label(pD, P(-2,-2), "$D$", bl);

  label(O, P(-12,2), "$O$", tl);

  label(pa1, P(2,2), "$a$", tr);
  label(pa2, P(4,4), "$a'$", tr);

  label(pb1, P(2,2), "$b$", tr);
  label(pb2, P(4,4), "$b'$", tr);

  label(P(xmax(),0), P(2,0), "$X_1$", r);
  label(P(0,ymax()), P(2,0), "$X_4$", br);

  label(polar(4, th), P(2,0), "$X_1'$", r);
  label(polar(4, 90-th), P(2,0), "$X_4'$", r);

  arc_arrow(O, Rad, 0.5*th, 0);
  arc_arrow(O, Rad, 0.5*th, th);

  arc_arrow(O, Rad, 90 - 0.5*th, 90);
  arc_arrow(O, Rad, 90 - 0.5*th, 90 - th);

  masklabel(polar(Rad, 0.5*th), "$\\theta$");
  masklabel(polar(Rad, 90 - 0.5*th), "$\\theta$");

  dashed();
  line(polar(-4,th), polar(4, th));
  line(polar(-4,90-th), polar(4, 90-th));

  dash_size(6);
  P tmp1(polar(2.75,90-th)), tmp2(polar(4, 90-th)), tmp3(tmp2.x1(), tmp1.x2());
  line(tmp1, tmp3);
  line(tmp2, tmp3);

  label(0.5*(tmp1+tmp3), P(0,-4), "$dx_1$", b);
  label(0.5*(tmp2+tmp3), P(4, 0), "$dx_4$", r);

  font_face("sc");
  label(P(0.5*(xmin() + xmax()),ymin()), P(0,-12), "Fig.~18.", b);
  tikz_format();
  end();
}