Convert Tableau function WINDOW_SUM into DAX

[Anonymous]

Hello,

I would like to convert the below Tableau expression into DAX:

WINDOW_SUM(sum([values]), -DATEDIFF('day',DATE('1/4/'+str(year(DATEADD('month',-3,attr([Date]))))),attr([Date])),0)

[Anonymous]

@Greg_Deckler , 
As I understand this formula, it starts summing up values on 1 April and restarts every year on the same date.
The first value is of 1 April, the second value is of 2 April + 3 April, the third value is of 3 April +4 April+5 April and so on.

[Greg_Deckler]

@Anonymous Maybe:

Cumulative April 1 =
  VAR __Date = MAX('Table'[Date])
  VAR __Year = IF(MONTH(__Date) < 4, YEAR(__Date) - 1 , YEAR(__Date))
  VAR __Table = FILTER(ALL('Table'), [Date] <= __Date && [Date] >= DATE(__Year, 4, 1))
  VAR __Result = SUMX(__Table, [Values])
RETURN
  __Result

[Anonymous]

@Greg_Deckler The formula works as a cumulative total. There window element is not there. 

[Greg_Deckler]

@Anonymous Right, the formula I provided is a cumulative total that resets on April 1st. There is a new WINDOW function in DAX. It's sort of kind of supposed to work at a "visual" level but that's not really how it works. 

If you want a cumulative total that resets on April 1st, the formula I provided should work. It dynamically creates the "window" in the __Table VAR.

[Anonymous]

@Greg_Deckler , here is a link and extract:

https://help.tableau.com/current/pro/desktop/en-us/functions_functions_tablecalculation.htm

[Greg_Deckler]

@Anonymous What does WINDOW_SUM do?