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

const double XMin(0.75);
const double a(sqrt(3)*XMin);
double dy(0.125);

double g(double x)
{
  x -= dy;
  double u((x-XMin)*(x-XMin));
  return 1.5 - 1.75*u/(1 + x);
}

P f(double x)
{
  return P(g(x), x);
}

double X0(0.75), dx(0.2);

double h1(double x) { return X0; }
double h2(double x) { return X0 + dx; }

double Y0(newton(g, h1, 0.33)), Y0a(newton(g, h2, 0.33));
double Y1(newton(g, h1, 2)), Y1a(newton(g, h2, 2));

int main()
{
  picture(P(0,0), P(2,2), "2.5 x 2in");

  begin();
  cme_bold();

  plot(f, 0.025 + dy, xmax() + dy, 60);

  P Q(f(XMin + dy)),
    Q0(X0, Y0), Q0a(X0 + dx, Y0), Q0b(f(Y0a)),
    Q1(X0, Y1), Q1a(X0 + dx, Y1), Q1b(f(Y1a));

  line(Q0, Q0a);
  line(Q0b, Q0a);

  line(Q1, Q1a);
  line(Q1b, Q1a);

  label(midpt(Q0, Q0a), P(0,-4), "$dx$", b);
  label(midpt(Q1, Q1a), P(0, 4), "$dx$", t);

  label(midpt(Q0a, Q0b), P(4, 0), "$dy$", r);
  label(midpt(Q1a, Q1b), P(4, 0), "$dy$", r);

  v_axis_tick(Q);
  label(Q, P(4,0), "$Q$", r);

  cme_dashed();
  line(P(X0,0), P(X0, Y1));
  line(P(X0 + dx,0), P(X0 + dx, Y1a));

  line(Q, Q&E_1);
  cme_solid();

  axis_labels();
  axes();

  caption("Fig.~18.");
  tikz_format();
  end();
}