require ("xfig");
require ("rand");
require ("histogram");

private define gauss_pdf (x, sigma)
{
   return 1.0/sqrt(2*PI*sigma^2) * exp(-0.5*x^2/sigma^2);
}

define slsh_main ()
{
   variable mu = 5, sigma = 1;
   variable data = mu + rand_gauss (sigma, 100);
   variable dx = 0.4;
   variable x = [min(data):max(data):dx];
   variable y = hist1d (data, x);
   variable dy = sqrt (y);
   variable xx = [mu-5*sigma:mu+5*sigma:0.1*dx];
   variable yy = (dx*length (data)) * gauss_pdf (xx-mu, sigma);

   variable w = xfig_plot_new ();
   w.world (min(x), max(x), 0.9, max(y)*1.1);
   w.plot (xx, yy);
   x += 0.5*dx;
   w.plot (x,y, dx, dy ; line=0, sym="diamond", color="blue1", width=3, size=5, fill=10);
   w.title ("Example with error bars");
   w.xlabel("$\lambda$ [\AA]"R);
   w.ylabel("Counts per bin"R);

   xfig_render_object (w, "errbar.png");
}