function h = collatz_height ( n )
%% collatz_height.m
%
  h = n;
  while ( n ~= 1 )
    if ( n % 2 == 0 )
      n = n / 2;
    else
      n = 3 * n + 1;
    end
    h = max ( h, n );
  end
  return
end
