function f = f09_f0 ( n, x, y )

%*****************************************************************************80
%
%% F09_F0 returns the value of function 9.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    29 January 2012
%
%  Author:
%
%    John Burkardt
%
%  Parameters:
%
%    Input, integer N, the number of evaluation points.
%
%    Input, real X(N,1), Y(N,1), the evalution points.
%
%    Output, real F(N,1), the function values.
%
  t1(1:n,1) = exp ( ( 10.0 - 20.0 * x(1:n,1) ) / 3.0 );
  t2(1:n,1) = exp ( ( 10.0 - 20.0 * y(1:n,1) ) / 3.0 );
  t3(1:n,1) = 1.0 ./ ( 1.0 + t1(1:n,1) );
  t4(1:n,1) = 1.0 ./ ( 1.0 + t2(1:n,1) );
  f(1:n,1) = ( ( 20.0 / 3.0 )^3 * t1(1:n,1) .* t2(1:n,1) ).^2 ...
    .* ( t3(1:n,1) .* t4(1:n,1) ).^5 ...
    .* ( t1(1:n,1) - 2.0 * t3(1:n,1) ) .* ( t2(1:n,1) - 2.0 * t4(1:n,1) );

  return
end