title: Apache POI and SUMPRODUCT formula evaluation
body: <p>I have a template XLS file that I load with Apache POI and write loads of data in it, then save it as another file.
  I have formulas in my XLS file like this:</p>
  
  <pre><code>=SUMPRODUCT((DS!B:B="IN_THIS_ONLY")*(DS!D:D="New trade"))
  </code></pre>
  
  <p>also tried</p>
  
  <pre><code>=SUMPRODUCT(0+(DS!B:B="IN_THIS_ONLY"),0+(DS!D:D="New trade"))
  </code></pre>
  
  <p>these evaluate correctly if I press Enter on the cell in Excel.
  However, simply calling</p>
  
  <pre><code>HSSFFormulaEvaluator.evaluateAllFormulaCells(workbook);
  </code></pre>
  
  <p>does not seem to evaluate them, neither does pressing on the "Calculate now" button in Excel - so I guess this is a special formula or function.</p>
  
  <p>The other, more conventional <code>COUNTIF</code>s and <code>SUMIF</code>s work fine, however these do not allow multiple conditions to be specified.</p>
  
  <p>POI does not support array formulas.</p>
  
  <p>Is there any way to make these work. I'm using POI version 3.7.</p>