site_percolation.ps

site-percolation, and translated it to ps files

%!PS-Adobe-2.0
%%  This PostScript program displays a site percolation configuration in
%%  different colors for each cluster.  Linear size L and probability p 
%%  can be changed at will.
%%
%%
/L 16 def                   % system is a square of L x L
/p 0.5 def                  % probability to occupy a site
%%
%%
/ip p 2147483647 mul def    % scale p to 0 to 2^31-1
%%  Define N = L^2, Nminus = N - 1, and array s
/N L dup mul def
/Nminus1 N 1 sub def
/s N array def              % s is an array with L^2 elements
%%
%% Define procedure Neighbors, the neighbors of site i
/Neighbors {                % Neighbors take a number from the
   /i exch def              % stack, generate neighbor sites
   i 1 add                  % of that site i.  The neighbor of site i
   dup L mod 0 eq {pop} if  % is i+1, i-1, i+L, i-L.  However,
   i L mod 0 ne {           % open boundary is used.  If the site  
      i 1 sub               % is at the edge, it does not have
   } if                     % neighbor outside.
   i L ge { i L sub } if 
   i N L sub lt { i L add } if 
} def
%%
%%  Define procedure XYcoordinate which convert site number i into
%%  (X,Y) pair by the X = i mod L,  Y = i/L.
/XYcoordinate {
   dup L mod exch
   L idiv 
} def
%%
%%  Define recursive procedure Color which draw a single cluster with  
%%  certain color.
/Color {                    % take a site from stack and color it.
   count 0 gt {             % If there are something on the stack,
      dup XYcoordinate      % Convert site number to (x,y) pair
      0.23 0 360 arc fill   % and draw a disc.
      [ exch Neighbors ]    % The neighbor sites is on the stack as array.
         { dup                   % if s[i] is 1, set it to 0 and  
            s exch get 1 eq {    % leave i on the stack, otherwise
            dup s exch 0 put }   % clear the stack
            { pop                % This is done for all the neighbors.
            } ifelse
         } forall
      Color
   } if
} def
%%
%%Page:1
%%  Write the title
/Helvetica findfont 13 scalefont setfont
150 80 moveto 
(Site Pecolation at p = ) show
/str 5 string def
p str cvs show
( with Size L = ) show
L str cvs show 
%%
%%  Translate and scale
50 150 translate
495 L 1 sub div dup scale
%%
usertime srand              % set random number seed
%%
%%  Generate site percolation configuration
0 1 Nminus1 {
   s exch 
   ip rand le {
      0}{1} ifelse
   put  
} for   
%%
%%  Draw square lattice grids
0.01 setlinewidth
0 0 0.7 setrgbcolor         % in blue color
/Lminus1 L 1 sub def        % define L - 1
0 1 Lminus1 {
   dup 0 moveto
   dup Lminus1 lineto       % vertical line (i,0) to (i,L-1)
   dup 0 exch moveto
   Lminus1 exch lineto      % horizontal line (0,i) to (L-1,i)
} for
stroke
%%
%%  Draw occupied sites as black discs.
0 0 0 setrgbcolor
newpath
0 1 Nminus1 {
   dup s exch get 1 eq {
      XYcoordinate
      0.3 0 360 arc fill }{
      pop
   } ifelse
} for
%%
%%  And finally, color each clusters with diffferent colors.
/inc 0 def
0 1 Nminus1 {
   dup s exch get 1 eq {
      inc 3 mod 2 div rand 4147483647.0 div add  
      inc 4 mod 3 div rand 8147483647.0 div add        
      inc 7 mod 6 div rand 6147483647.0 div add  
      /inc inc 1 add def
      setrgbcolor
      Color }{
      pop
   } ifelse
} for
%%
showpage
%%End