* @return non shared formula created for the given shared formula and this cell
*/
private String convertSharedFormula(int si){
XSSFSheet sheet = getSheet();
CTCellFormula f = sheet.getSharedFormula(si);
if(f == null) throw new IllegalStateException(
"Master cell of a shared formula with sid="+si+" was not found");
String sharedFormula = f.getStringValue();
//Range of cells which the shared formula applies to
String sharedFormulaRange = f.getRef();
CellRangeAddress ref = CellRangeAddress.valueOf(sharedFormulaRange);
int sheetIndex = sheet.getWorkbook().getSheetIndex(sheet);
XSSFEvaluationWorkbook fpb = XSSFEvaluationWorkbook.create(sheet.getWorkbook());