Set analysis : how to do-> sum({<date=previous(date in selection)>}quantity)

[EdgarB]

Hello, 

I have this set analysis : Sum({$<DAT_START={"$(=Max(DAT_START,2))"}>}[Net Quantity Ordered])

which works if I don't select a DAT_START value in filter pane. 

I Have 3 values in DAT_START : 

1/4/2020

1/10/2020

1/4/2021

Do you know how can I change this formula so it can be dynamic ? 

Thanks a lot

[marcus_sommer · Accepted solution]

Maybe this:

Sum({$<DAT_START={"$(=Max({1} DAT_START,2))"}>}[Net Quantity Ordered])

- Marcus