# File lib/classifier/lsi.rb, line 197
    def proximity_norms_for_content( doc, &block )
      return [] if needs_rebuild?
  
      content_node = node_for_content( doc, &block )
      result = 
        @items.keys.collect do |item|
          if $GSL
            val = content_node.search_norm * @items[item].search_norm.col
          else
            val = (Matrix[content_node.search_norm] * @items[item].search_norm)[0]
          end
          [item, val]
        end
      result.sort_by { |x| x[1] }.reverse
    end