title: Add Custom Calculations in the Column Footer using DynamicJasper in Excel report
body: <p>I am using <em>DynamicJasper</em> ver 4.0.2 and I've created the report in <em>Excel</em> format.</p>
  
  <p>The report is having three columns let say A, B and C.<br/>
  In the footer I want total of column A i.e. SUM(A) and Column B i.e. SUM(B) while total of Column C=(SUM(B)/SUM(A))*100.</p>
  
  <p>However I could able to add total for column A and B by using <code>drb.addGlobalFooterVariable(columnA, DJCalculation.SUM)</code> and <code>drb.addGlobalFooterVariable(columnB, DJCalculation.SUM)</code>.</p>
  
  <p>But I'm not able to find the Solution for columnC as per formula explained above.</p>
  
  <p>I googled but I didn't get any relevant post. Please help me.</p>