function distance_histogram ( n )

  p1 = rand(2,n);
  p2 = rand(2,n);
  d = vecnorm ( p1 - p2 );
  bins = 20;
  histogram ( d, bins, 'Normalization', 'pdf' )
  filename = 'distance_histogram.png';
  print ( '-dpng', filename );
  fprintf ( 1, '  Graphics saved as "%s"\n', filename );
  pause ( 5 )

  return
end

