One of the features, we´ve added to old jpivot is Formula Editor you can find in new STPivot, the new free and open source olap viewer you can download:
This feature allow users to add/edit calculated members or named sets, that are added to the query in the form of “with … member ...”. This entities list, also known as formulas, appears below the cube navigator in left panel. In the picture you can see the Formula Editor dialog, along with red marks indicating where are the buttons to open it.
You can follow our Video Tutorial for creating formulas in STPivot. Hope you enjoy it!!