function sparse_grid_display ( input_file_name, rmin, rmax )

%% SPARSE_GRID_DISPLAY displays a 2D or 3D sparse grid.
%
%  Modified:
%
%    22 April 2007
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  timestamp;

  fprintf ( 1, '\n' );
  fprintf ( 1, 'SPARSE_GRID_DISPLAY:\n' );
  fprintf ( 1, '  MATLAB version\n' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Display a 2D or 3D sparse grid.\n' );
%
%  First command line argument is the file name.
%
  if ( nargin < 1 )

    fprintf ( 1, '\n' );
    fprintf ( 1, 'SPARSE_GRID_DISPLAY:\n' );
    input_file_name = input ( 'Enter the name of the file containing the points:' );

  end
%
%  Second command line argument is the lower range.
%
  if ( nargin < 2 )

    fprintf ( 1, '\n' );
    fprintf ( 1, 'SPARSE_GRID_DISPLAY:\n' );
    rmin = input ( 'Enter the minimum value of the range:' );

  end
%
%  Third command line argument is the upper range.
%
  if ( nargin < 3 )

    fprintf ( 1, '\n' );
    fprintf ( 1, 'SPARSE_GRID_DISPLAY:\n' );
    rmax = input ( 'Enter the maximum value of the range:' );

  end
%
%  Load the data.
%  
  points = load ( input_file_name )';

  dim_num = size ( points, 1 );
  point_num = size ( points, 2 );
%
%  2D Plot
%
  if ( dim_num == 2 )
%
%  Clear the graphics frame;
%
    clf
%
%  We have to name the axes in order to control the grid.
%
    axes_handle = axes;
%
%  Plot the points.
%
    handle = scatter ( points(1,:), points(2,:), 'b', 'filled' );
%
%  Force the plotting region to be square, not rectangular.
%
    axis square
%
%  Request grid lines.
%
    grid on
%
%  Specify the location of the grid lines, and suppress labeling.
%
    rdelt = ( rmax - rmin ) / 8.0;
    ticks = rmin : rdelt : rmax;
  
    set ( axes_handle, 'xtick', ticks );
    set ( axes_handle, 'xticklabel', [] );
    set ( axes_handle, 'ytick', ticks );
    set ( axes_handle, 'yticklabel', [] );
%
%  Make the plotting region slightly bigger than the data.
%
    range = rmax - rmin;
    rmin1 = rmin - 0.05 * range;
    rmax1 = rmax + 0.05 * range;
    axis ( [ rmin1, rmax1, rmin1, rmax1 ] )

    xlabel ( '--X axis--' )
    ylabel ( '--Y axis--' )
%
%  Title
%
    title_string = s_escape_tex ( input_file_name );
    title ( title_string );
%
%  Make an output file name based on the input file name, but
%  with "PNG" extension.
%
    output_file_name = file_name_ext_swap ( input_file_name, 'png' );
%
%  Save the figure and write it out.
%
    frame = getframe;
    [ image, map ] = frame2im ( frame );

    imwrite ( image, output_file_name, 'PNG' );

    fprintf ( 1, '\n' );
    fprintf ( 1, 'SPARSE_GRID_DISPLAY\n' );
    fprintf ( 1, '  The input data "%s" was read in, and plotted\n', ...
      input_file_name );
    fprintf ( 1, '  in the PNG file "%s".\n', output_file_name );
%
%  3D plot
%
  elseif ( dim_num == 3 )
%
%  Clear the graphics frame;
%
    clf
%
%  We have to name the axes in order to control the grid.
%
    axes_handle = axes;
%
%  Plot the points.
%
    handle = scatter3 ( points(1,:), points(2,:), points(3,:), 'b', 'filled' );
%
%  Force the plotting region to be square, not rectangular.
%
    axis square
%
%  Request grid lines.
%
    grid on
%
%  Specify the location of the grid lines, and suppress labeling.
%
    rdelt = ( rmax - rmin ) / 8.0;
    ticks = rmin : rdelt : rmax;
  
    set ( axes_handle, 'xtick', ticks );
    set ( axes_handle, 'xticklabel', [] );
    set ( axes_handle, 'ytick', ticks );
    set ( axes_handle, 'yticklabel', [] );
    set ( axes_handle, 'ztick', ticks );
    set ( axes_handle, 'zticklabel', [] );
%
%  Make the plotting region slightly bigger than the data.
%
    range = rmax - rmin;
    rmin1 = rmin - 0.05 * range;
    rmax1 = rmax + 0.05 * range;
    axis ( [ rmin1, rmax1, rmin1, rmax1 ] )

    xlabel ( '--X axis--' )
    ylabel ( '--Y axis--' )
    zlabel ( '--Z axis--' )
%
%  Title
%
    title_string = s_escape_tex ( input_file_name );
    title ( title_string );
    
    view ( -10, 15 )
%
%  Make an output file name based on the input file name, but
%  with "PNG" extension.
%
    output_file_name = file_name_ext_swap ( input_file_name, 'png' );
%
%  Save the figure and write it out.
%
    frame = getframe;
    [ image, map ] = frame2im ( frame );

    imwrite ( image, output_file_name, 'PNG' );

    fprintf ( 1, '\n' );
    fprintf ( 1, 'SPARSE_GRID_DISPLAY\n' );
    fprintf ( 1, '  The input data "%s" was read in, and plotted\n', ...
      input_file_name );
    fprintf ( 1, '  in the PNG file "%s".\n', output_file_name );

  end
%
%  Terminate.
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'SPARSE_GRID_DISPLAY:\n' );
  fprintf ( 1, '  Normal end of execution.\n' );

  fprintf ( 1, '\n' );
  timestamp;