function volcano_plots ( )

%*****************************************************************************80
%
%% volcano_plots makes a line contour, color contour, and surface plots.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    08 October 2019
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'volcano_plots:\n' );
  fprintf ( 1, '  MATLAB version\n' );
  fprintf ( 1, '  Given an array of data about volcano height, make:\n' );
  fprintf ( 1, '  a line contour plot.\n' );
  fprintf ( 1, '  a color contour plot.\n' );
  fprintf ( 1, '  a surface plot.\n' );
%
%  Read the data from a file.
%
  z = load ( 'volcano_data.txt' );
  [ m, n ] = size ( z );
  fprintf ( 1, '  %d x %d data matrix\n', m, n );

  figure ( 1 );
  contour ( z, 'linewidth', 3 );
  xlabel ( '<-- X -->' );
  ylabel ( '<-- Y -->' );
  title ( 'Contour lines of volcano height' );
  filename = 'volcano_contour_line.png';
  print ( '-dpng', filename )
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Graphics saved as "%s"\n', filename );

  figure ( 2 );
  contourf ( z );
  colorbar ( );
  xlabel ( '<-- X -->' );
  ylabel ( '<-- Y -->' );
  title ( 'Color contours of volcano height' )
  filename = 'volcano_contour_color.png';
  print ( '-dpng', filename )
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Graphics saved as "%s"\n', filename );

  figure ( 3 );
  surf ( z, 'edgecolor', 'none' );
  colorbar ( );
  xlabel ( '<-- X -->' );
  ylabel ( '<-- Y -->' );
  zlabel ( '<-- Z -->' );
  title ( 'Surface plot of volcano height' );
  filename = 'volcano_surface.png';
  print ( '-dpng', filename )
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Graphics saved as "%s"\n', filename );
%
%  Terminate.
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'volcano_plots:\n' );
  fprintf ( 1, '  Normal end of execution.\n' );

  return
end

