using DevExpress.Spreadsheet;

Stream CalculateWorkbook(Stream inputStream, CalculationMode? documentCalculationMode, bool exportToPdf, DocumentFormat outputFormat) {
    using Workbook workbook = new Workbook();

    // Load the document
    workbook.LoadDocument(inputStream);

    // You can use different methods to force recalculation depending on your usage scenario.

    // The "Calculate" method recalculates values in cells marked for calculation and "CalculateAlways" cells:
    // -The cell contains a volatile function (IFunction.Volatile)
    // -The cell references another "CalculateAlways" cell
    // -The cell contains a circular reference
    workbook.Calculate();

    // The "CalculateFull" method forces recalculation of all spreadsheet cells regardless of whether the cell is marked for calculation.
    //workbook.CalculateFull();

    // The "CalculateFullRebuild" method forces a full recalculation of all spreadsheet cells and rebuilds the dependency tree (by default).
    // This method behavior depends on the DocumentOptions.CalculationEngineType value.
    // When DocumentOptions.CalculationEngineType is set to CalculationEngineType.Recursive CalculateFullRebuild and CalculateFull are equivalent.
    //workbook.CalculateFullRebuild();

    // Change the document calculation mode stored in the resulting document.
    if(documentCalculationMode.HasValue)
        workbook.DocumentSettings.Calculation.Mode = documentCalculationMode.Value;

    // Create output stream
    var outputStream = new MemoryStream();

    // Save document in target format
    if(exportToPdf)
        workbook.ExportToPdf(outputStream);
    else
        workbook.SaveDocument(outputStream, outputFormat);

    outputStream.Seek(0, SeekOrigin.Begin);

    return outputStream;
}