protected Double validateDoubleNotNegative(Row row, int idx, int format, boolean mandatory) {
        Cell cell = row.getCell(idx);
        boolean isValueNegativeOne = false;
        boolean isNaN = false;
        if (cell == null || cell.getCellType() == Cell.CELL_TYPE_BLANK ||
                (cell.getCellType() == Cell.CELL_TYPE_STRING && cell.getStringCellValue().isEmpty())) {
            return null;
        } else {
            //make sure its a number
            try {
                //makes sure the value from the user isn't -1 as opposed to the -1 returned by parseDouble below
                double num = cell.getNumericCellValue();
                if (num == -1.0) {
                    isValueNegativeOne = true;
                }
                isNaN = false;
            } catch (IllegalStateException e) {
                //could be an empty formula
                if (cell.getCellType() == Cell.CELL_TYPE_FORMULA) {
                    String str = cell.getStringCellValue();
                    if ( ! str.isEmpty()) {
                        //it's not an empty formula cell
                        isNaN = true;
                    }
                } else {
                    isNaN = true;
                }
            }
        }

        Double result = Utility.parseDouble(getCellValue(row, idx, format, mandatory) + "", -1);

        if(result == null || (result.equals(-1.0) && ! isValueNegativeOne && ! isNaN)) {
            return null;
        } else if (result != null && isNaN) {
            DataUploadCheckList mandatoryArgumentCheck = new DataUploadCheckList();
            mandatoryArgumentCheck.setSheetName(row.getSheet().getSheetName());
            mandatoryArgumentCheck.setCheckListFlag(DataUploadConstants.ERROR);
            mandatoryArgumentCheck.setDescription(
                    DataUploadConstants.INVALID_VALUE_ERROR
                    + cell.getRow().getSheet().getRow(0).getCell(cell.getColumnIndex()).getStringCellValue().replaceAll("\n", "").trim()
                    + DataUploadConstants.NAN_VALUE_ERROR);
            mandatoryArgumentCheck.setRowNumber((long) row.getRowNum());
            this.mandatoryAttributesErrorList.add(mandatoryArgumentCheck);
            result = null;
        } else if (result != null && result.doubleValue() < 0.0) {
            DataUploadCheckList mandatoryArgumentCheck = new DataUploadCheckList();
            mandatoryArgumentCheck.setSheetName(row.getSheet().getSheetName());
            mandatoryArgumentCheck.setCheckListFlag(DataUploadConstants.ERROR);
            mandatoryArgumentCheck.setDescription(
                    DataUploadConstants.INVALID_VALUE_ERROR
                    + cell.getRow().getSheet().getRow(0).getCell(cell.getColumnIndex()).getStringCellValue().replaceAll("\n", "").trim()
                    + DataUploadConstants.NEGATIVE_VALUE_ERROR);
            mandatoryArgumentCheck.setRowNumber((long) row.getRowNum());
            this.mandatoryAttributesErrorList.add(mandatoryArgumentCheck);
            result = null;
        }
        return result;
    }