function geyser_histogram ( )

%*****************************************************************************80
%
%% geyser_histogram() makes a histogram of geyser data.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    30 April 2018
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'geyser_histogram():\n' );
  fprintf ( 1, '  MATLAB/Octave version %s:\n', version ( ) );
  fprintf ( 1, '  Create a histogram of the time between eruptions\n' );
  fprintf ( 1, '  of the Old Faithful geyser.\n' );
%
%  Load the data.
%
  data = load ( 'geyser_data.txt' );

  [ m, n ] = size ( data );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  %d x %d data records read from file.\n', m, n );
%
%  Create a histogram.
%
  histogram ( data(:,1) );

  grid ( 'on' );
  title ( 'Time between eruptions of Old Faithful', 'Fontsize', 16 );
  xlabel ( 'Minutes', 'Fontsize', 16 );
  ylabel ( 'Frequency', 'Fontsize', 16 );
%
%  Save a copy of the plot as a PNG file.
%
  filename = 'geyser_histogram.png';
  print ( '-dpng', filename );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Graphic saved in "%s"\n', filename );
%
%  Terminate.
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'geyser_histogram():\n' );
  fprintf ( 1, '  Normal end of execution.\n' );

  return
end
