require ("grace");
require ("histogram");
require ("gslrand");

define slsh_main ()
{
   variable n = 500, sigma = 2, dx = 0.2;
   variable data = ran_gaussian (sigma, n);
   variable x = [min(data):max(data):dx];
   variable h = hist1d (data, x);
   variable y = dx * n * gaussian_pdf (x,sigma);

   variable g = grace_new ();
   g.multi (2,1;sizes=[3,1],vgap=0);
   g.focus(1,1);
   g.hplot (x,h,sqrt(h); sym=0,color="blue2",errbar_color=6,
	    fillpat=10,dropline,fill=2,fillcolor="cyan");
   g.oplot (x,y;color=2,line=1);
   g.title ("Simple residual plot");
   g.ylabel ("Counts/bin");

   g.focus(2,1);
   g.plot (x, h-h);
   g.oplot(x, h-y, sqrt(h); sym=-3,color=4, symfill=1, symsize=0.5, errbar_size=0,errbar_color=6);
   g.xlabel ("X");
   g.save ("/tmp/residual.ps");
}