function region = p21_region ( )

%*****************************************************************************80
%
%% P21_REGION returns the name of the integration region for problem 21.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    18 March 2007
%
%  Author:
%
%    John Burkardt
%
%  Output:
%
%    string REGION, the name of the integration region.
%
  region = 'sphere';

  return
end
