function h = predator_conserved ( y )

%*****************************************************************************80
%
%% predator_conserved evaluates a quantity that should be conserved.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    01 November 2020
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    real Y(:,2): solution values.
%
%  Output:
%
%    real H(:): the value of a quantity that should be conserved.
%
  [ alpha, beta, gamma, delta ] = predator_parameters ( );

  u = y(:,1);
  v = y(:,2);

  h =  delta * u  - gamma * log ( u )  + beta * v  - alpha * log ( v );

  return
end

