function oregonator_ode23 ( )

%*****************************************************************************80
%
%% oregonator_ode23() solves oregonator_ode() using ode23().
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    23 April 2021
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'oregonator_ode23():\n' );
  fprintf ( 1, '  Solve oregonator_ode() using ode23().\n' );

  [ eta1, eta2, q, f, t0, y0, tstop ] = oregonator_parameters ( );

  f = @ oregonator_deriv;
  tspan = [ t0, tstop ];
  [ t, y ] = ode23 ( f, tspan, y0 );

  n = size ( t, 1 );

  fprintf ( 1, '\n' );
  fprintf ( 1, '  Number of variable size steps = %d\n', n );
%
%  Plot x.
%
  figure ( 1 );
  clf ( );
  plot ( t, log10 ( y(:,1) ), 'b-', 'linewidth', 2 );
  grid ( 'on' );
  xlabel ( '<-- Time -->' );
  ylabel ( '<-- log10(x(t)) -->' );
  title ( 'oregonator_ode(): ode23: log10(x(t))' );
  filename = 'oregonator_ode23_x.png';
  print ( '-dpng', filename );
  fprintf ( 1, '  Graphics saved in "%s"\n', filename );
%
%  Plot y.
%
  figure ( 2 );
  clf ( );
  plot ( t, log10 ( y(:,2) ), 'b-', 'linewidth', 2 );
  grid ( 'on' );
  xlabel ( '<-- Time -->' );
  ylabel ( '<-- log10(y(t)) -->' );
  title ( 'oregonator_ode(): ode23: log10(y(t))' );
  filename = 'oregonator_ode23_y.png';
  print ( '-dpng', filename );
  fprintf ( 1, '  Graphics saved in "%s"\n', filename );
%
%  Plot z.
%
  figure ( 3 );
  clf ( );
  plot ( t, log10 ( y(:,3) ), 'b-', 'linewidth', 2 );
  grid ( 'on' );
  xlabel ( '<-- Time -->' );
  ylabel ( '<-- log10(z(t)) -->' );
  title ( 'oregonator_ode(): ode23: log10(z(t))' );
  filename = 'oregonator_ode23_z.png';
  print ( '-dpng', filename );
  fprintf ( 1, '  Graphics saved in "%s"\n', filename );
%
%  3D Plot xyz.
%
  figure ( 4 );
  clf ( );
  plot3 ( log10 ( y(:,1) ), log10 ( y(:,2) ), log10 ( y(:,3) ), ...
    'b-', 'linewidth', 2 );
  grid ( 'on' );
  xlabel ( '<-- log10(x(t)) -->' );
  ylabel ( '<-- log10(y(t)) -->' );
  zlabel ( '<-- log10(z(t)) -->' );
  title ( 'oregonator_ode(): ode23: log10(x,y,z)' );
  filename = 'oregonator_ode23_xyz.png';
  print ( '-dpng', filename );
  fprintf ( 1, '  Graphics saved in "%s"\n', filename );

  return
end

