# File lib/asciidoctor/table.rb, line 126
  def assign_col_widths width_base = nil
    pf = 10.0 ** 4 # precision factor (multipler / divisor) for managing precision of calculated result
    total_width = col_pcwidth = 0

    if width_base
      @columns.each {|col| total_width += (col_pcwidth = col.assign_width nil, width_base, pf) }
    else
      col_pcwidth = ((100 * pf / @columns.size).to_i) / pf
      col_pcwidth = col_pcwidth.to_i if col_pcwidth.to_i == col_pcwidth
      @columns.each {|col| total_width += col.assign_width col_pcwidth }
    end

    # donate balance, if any, to final column
    @columns[-1].assign_width(((100 - total_width + col_pcwidth) * pf).round / pf) unless total_width == 100

    nil
  end