title: Formula Evaluator for XIRR function in Java
body: <p>Facing issue with reading a cell in excel which is set with XIRR function. 
  I written my code in Java. Below is the code to set the formula. Please help on how can I read the value from the cell and not the formula.</p>
  
  <pre><code>cell.setCellFormula("XIRR(E2:E10, B2:B10");        
  CellStyle style = workbook.createCellStyle();
  style.setDataFormat(workbook.createDataFormat().getFormat("0.00%"));
  cell.setCellStyle(style);
  </code></pre>
  
  <p>Below is the error while evaluating the cell using <strong>FormulaEvaluator</strong></p>
  
  <pre><code> org.apache.poi.ss.formula.eval.NotImplementedFunctionException: XIRR
      at org.apache.poi.ss.formula.atp.AnalysisToolPak$NotImplemented.evaluate(AnalysisToolPak.java:59)
      at org.apache.poi.ss.formula.UserDefinedFunction.evaluate(UserDefinedFunction.java:61)
      at org.apache.poi.ss.formula.OperationEvaluatorFactory.evaluate(OperationEvaluatorFactory.java:129)
      at org.apache.poi.ss.formula.WorkbookEvaluator.evaluateFormula(WorkbookEvaluator.java:550)
      at org.apache.poi.ss.formula.WorkbookEvaluator.evaluateAny(WorkbookEvaluator.java:317)
      ... 18 more
  </code></pre>