ReportPlus allows you to define new fields in the data set, named calculated fields. These fields are built based on expressions that may compose existing fields, constant values, and a set of predefined functions. In order to add a new calculated field, you must click the + button in the top bar of the left hand panel. Once you do it, you will be prompted to enter a name for the new field and the expression to calculate the value of the field.
For both field calculated fields (commonly referred to as "pre" calculated fields) and pivot table calculated fields ("post" calculated fields), you can use one of the available functions within ReportPlus:
Text strings should be included between quotation marks. Examples include locale ("en") and date formats ("dd/mm/yyyy").
Fields included in your formula should be included between square brackets. Examples include [Wage], [BirthDate] and [EmployeeID] for the HR Dataset.
Calculated fields are evaluated prior to executing pivot table aggregations. If you need calculation to take place after the summarization of the pivot table then you should use Pivot Table Calculated Fields.
When working with SSAS as your data source, you can only create "post" calculated fields. These are calculations that rely on already summarized values; the fields that appear in the Calculated Fields editor are the ones dropped in the "Rows" or "Values" placeholder of the pivot table.
If you need to define calculated members for Analysis Services, you can go through the Cube Designer’s Calculations tab.