12 Weeks Moving average using upper limit of date range

[AmritaD]

Date range is compulsory in my Sheet. Need to calculate 12 week moving average of an expression in a line chart.

12 weeks should start from upper limit of the date range and should consider a period of 12weeks from there in the past.

On selecting the date range less than 12weeks, the range of 12 weeks is not getting completed hence the result is incorrect.

Is there a way to choose only the max of date range and ignoring lower limit of the date range

[Anil_Babu_Samineni]

@AmritaD 

#1, I would think to add conditional error, If you have select lesser than 12 weeks, please get prompt message saying, you have selected lesser than 12 weeks. 

#2, Do you mean, If you select the max date, you want to fetch data only for that date selected and ignore all lower one? better to explain with data points.