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

const double mult(1.0/sqrt(M_PI));

double f(double x)
{
  return 0.4*exp(-mult*x*x);
}

double g(double x)
{
  return f(x-3);
}

double PAD_X(0.4), PAD_Y(0.01);

int main() {
  picture(P(-3-PAD_X, -PAD_Y), P(8+PAD_X, 0.4+PAD_Y), "5 x 3.5in");

  begin();
  border();

  legend L;
  L.border(0);

  fill(Black(0.2));
  shadeplot(g, 1.96, xmax(), 120);
  L.fill_item("$P(|Z|>1.96, H_1) = 0.85$");

  fill(Black(0.8));
  shadeplot(f, xmin(), -1.96, 20);
  shadeplot(f, 1.96, 4, 40);
  L.fill_item("$P(|Z|>1.96, H_0) = 0.05$");

  plot(f, xmin(), xmax(), 240);
  plot(g, xmin(), xmax(), 240);

  font_size("scriptsize");
  L.draw(P(4,0.35), P(0,0), tr);

  label(P(0, 0.15), P(0,2), "$H_0$: $\\mu_1=\\mu_2$", t);
  label(P(2, 0.15), P(2,2), "$H_1$: $\\mu_1=\\mu_2+\\delta$", tr);

  font_size("footnotesize");
  axis Ax(P(-2, ymin()), P(8, ymin()), 5, P(0,-8), b);
  Ax.align(b).draw();

  label(P(2, ymin()), P(0,-18),
	"$Z=\\displaystyle\\frac{\\mu_1-\\mu_2}{\\sigma/\\sqrt{\\pi}}$", b);

  degrees();
  label_angle(90);

#ifdef OLD_GCC
  axis Ay(P(-3.4, 0), P(xmin(), 0.4), 4, P(-8,0), l);
#else
  // may not compile under gcc <= 3.3
  axis Ay(P(xmin(), 0), P(xmin(), 0.4), 4, P(-8,0), l);
#endif

  Ay.align(l).draw();

  label(P(xmin(), 0.2), P(-18,0), "Density", l);

  pst_format();
  end();
}