class Asciidoctor::Table

def assign_column_widths width_base = nil, autowidth_cols = nil

returns nothing

width_base - the total of the relative column values used for calculating percentage widths (default: nil)

This method assumes there's at least one column in the columns array.

donates the balance to the final column.
This method rounds the percentage width values to 4 decimal places and

Internal: Assign column widths to columns 
def assign_column_widths width_base = nil, autowidth_cols = nil
  precision = DEFAULT_PRECISION
  total_width = col_pcwidth = 0
  if width_base
    if autowidth_cols
      if width_base > 100
        autowidth = 0
        logger.warn %(total column width must not exceed 100% when using autowidth columns; got #{width_base}%)
      else
        autowidth = ((100.0 - width_base) / autowidth_cols.size).truncate precision
        autowidth = autowidth.to_i if autowidth.to_i == autowidth
        width_base = 100
      end
      autowidth_attrs = { 'width' => autowidth, 'autowidth-option' => '' }
      autowidth_cols.each {|col| col.update_attributes autowidth_attrs }
    end
    @columns.each {|col| total_width += (col_pcwidth = col.assign_width nil, width_base, precision) }
  else
    col_pcwidth = (100.0 / @columns.size).truncate precision
    col_pcwidth = col_pcwidth.to_i if col_pcwidth.to_i == col_pcwidth
    @columns.each {|col| total_width += col.assign_width col_pcwidth, nil, precision }
  end
  # donate balance, if any, to final column (using half up rounding)
  @columns[-1].assign_width(((100 - total_width + col_pcwidth).round precision), nil, precision) unless total_width == 100
  nil
end