NPOI.XSSF.UserModel.XSSFWorkbook.GetCreationHelper C# (CSharp) Method

        public ICreationHelper GetCreationHelper()
        {
            if (_creationHelper == null) _creationHelper = new XSSFCreationHelper(this);
            return _creationHelper;
        }

        public void TestSharedFormulas_EvaluateInCell()
        {
            XSSFWorkbook      wb        = (XSSFWorkbook)_testDataProvider.OpenSampleWorkbook("49872.xlsx");
            IFormulaEvaluator Evaluator = wb.GetCreationHelper().CreateFormulaEvaluator();
            ISheet            sheet     = wb.GetSheetAt(0);

            double result = 3.0;

            // B3 is a master shared formula, C3 and D3 don't have the formula written in their f element.
            // Instead, the attribute si for a particular cell is used to figure what the formula expression
            // should be based on the cell's relative location to the master formula, e.g.
            // B3:        <f t="shared" ref="B3:D3" si="0">B1+B2</f>
            // C3 and D3: <f t="shared" si="0"/>

            // Get B3 and Evaluate it in the cell
            ICell b3 = sheet.GetRow(2).GetCell(1);

            Assert.AreEqual(result, Evaluator.EvaluateInCell(b3).NumericCellValue);

            //at this point the master formula is gone, but we are still able to Evaluate dependent cells
            ICell c3 = sheet.GetRow(2).GetCell(2);

            Assert.AreEqual(result, Evaluator.EvaluateInCell(c3).NumericCellValue);

            ICell d3 = sheet.GetRow(2).GetCell(3);

            Assert.AreEqual(result, Evaluator.EvaluateInCell(d3).NumericCellValue);
        }