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

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

int main()
{
  picture(P(-3.5,-2), P(5.5,10), "2.75 x 2.25in");

  begin();

  cme_bold();
  set_crop();

  line(P(xmin(),0), P(xmax(),0));
  h_axis_labels(P(-3,0), P(-1,0), 2, P(-1,6), t);
  h_axis_labels(P( 1,0), P(5,0), 4, P(0,-3), b);

  line(P(0,-2), P(0,0));
  v_axis(P(0,-1), P(0, 9), 10);
  v_axis_labels(P(0,1), P(0,5), 4, P(-4,0), l);

  label(P(xmax(),0), P(4,0), "$x$", r);
  label(P(0,ymax()), P(-4,0), "$\\dfrac{dy}{dx}$", bl);

  cme_dashed();
  for (int i=-2; i <= 5; ++i)
    if (i != 0)
      {
	P tmp(i, f(i));
	line(tmp, tmp&E_1);
	line(tmp, tmp&E_2);
      }

  masklabel(P(0,0), P(0,-1), "$0$", b);

  cme_solid();
  double X0(3.);
  label_angle(Atan(0.5));

  masklabel(P(X0, f(2)), P(0,2), "$\\dfrac{dy}{dx} = \\frac{1}{2}x$", t);

  plot(f, -3.05, xmax(), 1);

  label_angle(0);
  caption("Fig.~24.");
  tikz_format();
  end();
}