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

double f(double x)
{
  return 0.5 + 0.375*x*x;
} 

double X0(0.75), dx(0.2), X1(1.5);

int main()
{
  picture(P(-1.25,0), P(2,2), "3.5 x 2in");

  begin();
  cme_bold();

  plot(f, xmin(), xmax(), 40);

  P Q0(X0, f(X0)), Q0a(X0 + dx, f(X0 + dx)), Q0b(Q0a.x1(), Q0.x2());
  P Q1(X1, f(X1)), Q1a(X1 + dx, f(X1 + dx)), Q1b(Q1a.x1(), Q1.x2());

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

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

  cme_dashed();
  line(Q0, Q0&E_1);
  line(Q0a, Q0a&E_1);

  line(Q1, Q1&E_1);
  line(Q1a, Q1a&E_1);

  label(P(0, f(0)), P(2,2), "$P$", tr);
  label(Q0, P(-2,2), "$Q$", t);
  label(Q1, P(-4,2), "$R$", t);

  smallbrace(P(0,f(0)), P(0,0), "$b$");
  cme_solid();
  axis_labels();
  axes();

  caption("Fig.~22.");
  tikz_format();
  end();
}