--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc/interpreter/geometryimages.m	Sat Aug 25 00:35:43 2007 +0000
@@ -0,0 +1,133 @@
+function geometryimages (nm, typ)
+  bury_output ();
+  if (strcmp (nm, "voronoi"))
+    rand("state",9);
+    x = rand(10,1);
+    y = rand(10,1);
+    tri = delaunay (x, y);
+    [vx, vy] = voronoi (x, y, tri);
+    triplot (tri, x, y, "b");
+    hold on;
+    plot (vx, vy, "r");
+    [r, c] = tri2circ (tri(end,:), x, y);
+    pc = [-1:0.01:1];
+    xc = r * sin(pi*pc) + c(1);
+    yc = r * cos(pi*pc) + c(2);
+    plot (xc, yc, "g-", "LineWidth", 3);
+    axis([0, 1, 0, 1]);
+    legend ("Delaunay Triangulation", "Voronoi Diagram");
+    print (strcat (nm, ".", typ), strcat ("-d", typ))    
+  elseif (strcmp (nm, "triplot"))
+    rand ("state", 2)
+    x = rand (20, 1);
+    y = rand (20, 1);
+    tri = delaunay (x, y);
+    triplot (tri, x, y);
+    print (strcat (nm, ".", typ), strcat ("-d", typ))    
+  elseif (strcmp (nm, "griddata"))
+    rand("state",1);
+    x=2*rand(1000,1)-1;
+    y=2*rand(size(x))-1;
+    z=sin(2*(x.^2+y.^2));
+    [xx,yy]=meshgrid(linspace(-1,1,32));
+    griddata(x,y,z,xx,yy);
+    print (strcat (nm, ".", typ), strcat ("-d", typ))    
+  elseif (strcmp (nm, "convhull"))
+    x = -3:0.05:3;
+    y = abs (sin (x));
+    k = convhull (x, y);
+    plot (x(k),y(k),'r-',x,y,'b+');
+    axis ([-3.05, 3.05, -0.05, 1.05]);
+    print (strcat (nm, ".", typ), strcat ("-d", typ)) 
+  elseif (strcmp (nm, "delaunay"))
+    rand ("state", 1);
+    x = rand (10, 1);
+    y = rand (10, 1);
+    T = delaunay (x, y);
+    X = [ x(T(:,1)); x(T(:,2)); x(T(:,3)); x(T(:,1)) ];
+    Y = [ y(T(:,1)); y(T(:,2)); y(T(:,3)); y(T(:,1)) ];
+    axis ([0, 1, 0, 1]);
+    plot(X, Y, "b", x, y, "r*");
+    print (strcat (nm, ".", typ), strcat ("-d", typ)) 
+  else
+    error ("unrecognized plot requested");
+  endif
+  bury_output ();
+endfunction
+
+function [r, c] = tri2circ (tri, xx, yy)
+  x = xx(tri);
+  y = yy(tri);
+  m = (y(1:end-1) - y(2:end)) ./ (x(1:end-1) - x(2:end));
+  xc = (prod(m) .* (y(1) - y(end)) + m(end)*(x(1)+x(2)) - m(1)*(x(2)+x(3))) ...
+        ./ (2 * (m(end) - m(1))); 
+  yc = - (xc - (x(2) + x(3))./2) ./ m(end) + (y(2) + y(3)) / 2;
+  c = [xc, yc];
+  r = sqrt ((xc - x(1)).^2 + (yc - y(1)).^2);
+endfunction
+
+## Use this function before plotting commands and after every call to
+## print since print() resets output to stdout (unfortunately, gnpulot
+## can't pop output as it can the terminal type).
+function bury_output ()
+  f = figure (1);
+  set (f, "visible", "off");
+endfunction
+function geometryimages (nm, typ)
+  bury_output ();
+  if (strcmp (nm, "voronoi"))
+    rand("state",9);
+    x = rand(10,1);
+    y = rand(10,1);
+    tri = delaunay (x, y);
+    [vx, vy] = voronoi (x, y, tri);
+    triplot (tri, x, y, "b");
+    hold on;
+    plot (vx, vy, "r");
+    [r, c] = tri2circ (tri(end,:), x, y);
+    pc = [-1:0.01:1];
+    xc = r * sin(pi*pc) + c(1);
+    yc = r * cos(pi*pc) + c(2);
+    plot (xc, yc, "g-", "LineWidth", 3);
+    axis([0, 1, 0, 1]);
+    legend ("Delaunay Triangulation", "Voronoi Diagram");
+    print (strcat (nm, ".", typ), strcat ("-d", typ))    
+  elseif (strcmp (nm, "triplot"))
+    rand ("state", 2)
+    x = rand (20, 1);
+    y = rand (20, 1);
+    tri = delaunay (x, y);
+    triplot (tri, x, y);
+    print (strcat (nm, ".", typ), strcat ("-d", typ))    
+  elseif (strcmp (nm, "griddata"))
+    rand("state",1);
+    x=2*rand(1000,1)-1;
+    y=2*rand(size(x))-1;
+    z=sin(2*(x.^2+y.^2));
+    [xx,yy]=meshgrid(linspace(-1,1,32));
+    griddata(x,y,z,xx,yy);
+    print (strcat (nm, ".", typ), strcat ("-d", typ))    
+  else
+    error ("unrecognized plot requested");
+  endif
+  bury_output ();
+endfunction
+
+function [r, c] = tri2circ (tri, xx, yy)
+  x = xx(tri);
+  y = yy(tri);
+  m = (y(1:end-1) - y(2:end)) ./ (x(1:end-1) - x(2:end));
+  xc = (prod(m) .* (y(1) - y(end)) + m(end)*(x(1)+x(2)) - m(1)*(x(2)+x(3))) ...
+        ./ (2 * (m(end) - m(1))); 
+  yc = - (xc - (x(2) + x(3))./2) ./ m(end) + (y(2) + y(3)) / 2;
+  c = [xc, yc];
+  r = sqrt ((xc - x(1)).^2 + (yc - y(1)).^2);
+endfunction
+
+## Use this function before plotting commands and after every call to
+## print since print() resets output to stdout (unfortunately, gnpulot
+## can't pop output as it can the terminal type).
+function bury_output ()
+  f = figure (1);
+  set (f, "visible", "off");
+endfunction