function h = ozone2_conserved ( y )

%*****************************************************************************80
%
%% ozone2_conserved() evaluates conservation for ozone2_ode().
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    26 January 2021
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Willem Hundsdorfer, Jan Verwer,
%    Numerical solution of time-dependent advection-diffusion-reaction equations,
%    Springer, 2003
%    ISBN: 978-3-662-09017-6
%
%  Input:
%
%    real Y(4): the current solution.
%
%  Output:
%
%    real H: the conserved quantity.
%
  y1 = y(:,1);
  y2 = y(:,2);
  y3 = y(:,3);
  y4 = y(:,4);

  h = y1 + y3 + y4;

  return
end
