function title = p21_title ( dummy )

%% P21_TITLE returns the title of problem 21.
%
%  Modified:
%
%    09 April 2007
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Output, string TITLE, the title of the problem.
%
  title = 'f(x,y) = 1 / r = 1 / sqrt ( x^2 + y^2 )';