function showpc ( )
%
%% showpc() plots absolute error for fixed step size Adams PC
% solution to y' = y, y(0) = 1 across [0,5].

  fprintf ( 1, '\n' );
  fprintf ( 1, 'showpc():\n' );

   E = zeros(5,5);
   for i=1:5
      n = 16*2^i;
      Exact = exp(-linspace(0,5,n+1));
      for k=1:5  
    [tvals,yvals] = FixedPC('f1',0,1,5/n,k,n);
	     E(i,k) = max(abs(yvals-Exact))
	  end
   end
   semilogy([32 64 128 256 512]',E)
   title('Adams PC on y''(t) = -y(t), y(0) = 1, 0<=t<=5, h = 5/n')
   xlabel('n (Number of Steps)')
   ylabel('Maximum absolute error')
   text(530,E(5,1),'k=1')
   text(530,E(5,2),'k=2')
   text(530,E(5,3),'k=3')
   text(530,E(5,4),'k=4')
   text(530,E(5,5),'k=5')
   axis([0 600 1e-12 1e-1])

  filename = 'showpc.png';
  print ( '-dpng', filename );
  fprintf ( 1, '  Graphics saved as "%s"\n', filename );

  return
end

