function fpx = fp_lotka ( n, x )

%*****************************************************************************80
%
%% fp_lotka() defines the jacobian of the implicit function for the Lotka problem.
%
%  Discussion:
%
%    The function is
%
%      fx(1) = x(1) - log ( x(1) ) + x(2) - 2.0 * log ( x(2) ) - 6.0 + log ( 16.0 );
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    15 September 2019
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    integer N, the number of variables, which should be 2.
%
%    real X(N), the variable values.
%
%  Output:
%
%    real FPX(N-1,N), the jacobian of the function evaluated at X.
%
  fpx = zeros ( n - 1, n );

  fpx(1,1) = 1.0 - 1.0 / x(1);
  fpx(1,2) = 1.0 - 2.0 / x(2);

  return
end
