Coding TOTALWTD

Hi,

I need to get the sum of values of a week.

For example, I choose the 19/09/2019 and that's showing me the sum of the values of a column for the 16/09 to the 19/09.

It's like the TOTALMTD function or the TOTALYTD function but for the week.

I tried a lot of things but I didn't success atm.

If anyone know the soluce or have an idea :)

Thanks,