Method updateFormula

src/backend/core/column/ColumnPrivate.cpp:2496–2606

! * \sa FunctionValuesDialog::generate() */

 * \sa FunctionValuesDialog::generate()
 */
void ColumnPrivate::updateFormula() {
	if (m_formula.isEmpty())
		return;
	DEBUG(Q_FUNC_INFO)
	// determine variable names and the data vectors of the specified columns
	QVector<QVector<double>*> xVectors;

	bool valid = true;
	QStringList formulaVariableNames;
	int maxRowCount = 0;

	auto numberLocale = QLocale();
	// need to disable group separator since parser can't handle it
	numberLocale.setNumberOptions(QLocale::OmitGroupSeparator);

	for (const auto& formulaData : m_formulaData) {
		auto* column = formulaData.column();
		if (!column) {
			valid = false;
			break;
		}
		formulaVariableNames << formulaData.variableName();

		if (column->columnMode() == AbstractColumn::ColumnMode::Double)
			xVectors << static_cast<QVector<double>*>(column->data());
		else {
			// convert integers to doubles first
			auto* xVector = new QVector<double>(column->rowCount());
			for (int i = 0; i < column->rowCount(); ++i)
				(*xVector)[i] = column->valueAt(i);

			xVectors << xVector;
		}

		if (column->rowCount() > maxRowCount)
			maxRowCount = column->rowCount();
	}

	if (valid) {
		// resize the spreadsheet if one of the data vectors from
		// other spreadsheet(s) has more elements than the parent spreadsheet
		// and if the option "auto resize" is activated
		if (m_formulaAutoResize && rowCount() < maxRowCount) {
			auto* spreadsheet = static_cast<Spreadsheet*>(q->parentAspect());
			// In the tests spreadsheet might not exist, because directly the column was created
			if (spreadsheet)
				spreadsheet->setRowCount(maxRowCount);
		}

		// create new vector for storing the calculated values
		// the vectors with the variable data can be smaller then the result vector. So, not all values in the result vector might get initialized.
		//->"clean" the result vector first
		QVector<double> new_data(rowCount(), NAN);

		const auto payload = std::make_shared<PayloadColumn>(m_formulaData, new_data);

		// evaluate the expression for f(x_1, x_2, ...) and write the calculated values into a new vector.
		auto* parser = ExpressionParser::getInstance();