function abm_wolfram

gr_sz = 40; % grid size
iterations = 19;  

% define initial state
x = round(rand(1,gr_sz));

for it = 1:iterations

  % left boundary
  nbhd = x(it,1) + x(it,2);
  if ( nbhd >= 1 )
    x(it+1,1) = 1;
  else
     x(it+1,1) = 0;
  end

  % interior
  for i = 2:(gr_sz-1) 
    nbhd = x(it,i-1) + x(it,i) + x(it,i+1);
    if ( nbhd >= 1 )
      x(it+1,i) = 1;
    else
      x(it+1,i) = 0;
    end
  end
  
  % right boundary
  nbhd = x(it,gr_sz) + x(it,gr_sz-1);
  if ( nbhd >= 1 ) 
    x(it+1,gr_sz) = 1;
  else
     x(it+1,gr_sz) = 0;
  end

end

% pcolor does not plot the last row for some reason
% so we copy the last row twice:
% x(:,gr_sz+1) = x(:,gr_sz);

pcolor( 1 - x );
colormap bone; % gray bone;
shading flat; % flat faceted interp

xlabel('grid space');
ylabel('time iterations')