# File split/Dvector/lib/Dvector_extras.rb, line 277
    def Dvector.write(file, cols, options = {})
      ops = WRITE_DEFAULTS.update(options)
      if file.is_a?(String)
        file = File.open(file, ops["write_mode"])
      end 
      nb = cols.map {|d| d.size}.max # The number of lines
      nb.times do |i|
        file.puts(cols.map {|d| d[i].to_s }.join(ops["sep"]))
      end
    end