Matrix-type grid - HELP?!?!

Hi all, I have a billing application in which I want to create a matrix-type view of period billings by accounting number and by period. It's almost working, but not quite, and I'm not Rails-savvy enough to take it further. Can anyone point me in the right direction? Thanks in advance! -Katie

The app is on github so you can see the models, joins, etc: https://github.com/sdstoic/billing/tree/master/app

CONTROLLER (period_billings):

  def period_billings     @sla = Sla.find(params[:sla_id])   @current_period = PeriodCounter.first.period.pe_number     @period_billings = @sla.period_billings.sort_by { |pb| [pb.period.pe_number, pb.general_ledger.general_ledger_number] }     @billings = Array.new(@period_billings.collect { |pb| pb.general_ledger.general_ledger_number }).uniq.sort_by { |gl| gl }     @periods = Period.where("fiscal_year = ?", @sla.fiscal_year)     @general_ledgers = GeneralLedger.sla_related     @total_period_billings = @sla.period_billings.group_by(&:general_ledger_id)   #@sum_current_amt = @sla.period_billings.sum(current_amt).group_by(&:general_ledger_id)     respond_to do |format|       format.html # index.html.erb       format.xml { render :xml => @period_billings }     end   end

VIEW (_period_billings.html.erb):

<% @cumulative_total = 0 %>

<div id="gl_crosstab">   <table>     <tr>       <th>Period</th>       <% @general_ledgers.each do |g| %>         <th><%= g.general_ledger_number %></th>       <% end %>       <th>Total</th>       <th>% Expended</th>     </tr>     <% @period_billings.group_by(&:general_ledger_id).each do |pb| %>       <tr>         <td><%= pb[1].first.period.pe_number %></td>         <% pb[1].each do |p| %>       <td>       <% @sum_current_amt = pb[1].inject(0){|sum,p| sum + p.current_amt.to_i} %>           <%= number_to_currency(@sum_current_amt) %>       </td>         <% end %>         <td>           <% @cumulative_total = @cumulative_total + pb[1].inject(0){| sum,billing| sum+billing.current_amt.to_i} %>           <%= number_to_currency( @cumulative_total ) %> </td>         <td><%= number_to_currency((@cumulative_total/ @sla.project_total)*100) %> % </td>       </tr>     <% end %>

  </table> </div>