Help- Dax measure to calculate Exponential weighted moving average (EWMA)

[LijieWang]

I got the data as below: Column A and B are the raw data, Column C (EWMA) is calculated in Excel, the formula is : 

EWMAn =Current Weekly Amount *0.2+ previous EWMA*0.8, while EWMA0 (first row) = current amount*0.2+average all weekly amount*0.8 

Any way to calculate using DAX in Power BI as the formula need to refer to the previous row in the same column. 

Thanks in Advance

Lijie

Week/c	Weekly Amount	EWMA	Calculation
01/01/2018	105,000	114,758	b2*0.2+Average (b2:b63)*0.8
08/01/2018	108,000	113,406	B3*0.2+D2*0.8
15/01/2018	97,770	110,279	B4*0.2+D3*0.8
22/01/2018	89,000	106,023	B5*0.2+D4*0.8
29/01/2018	86,156	102,050
05/02/2018	83,746	98,389
12/02/2018	83,000	95,311
19/02/2018	85,000	93,249
26/02/2018	76,000	89,799
05/03/2018	90,000	89,839
12/03/2018	90,720	90,015
19/03/2018	89,000	89,812
26/03/2018	66,000	85,050
02/04/2018	92,100	86,460
09/04/2018	90,000	87,168
16/04/2018	87,000	87,134
23/04/2018	97,000	89,107
30/04/2018	85,000	88,286
07/05/2018	91,000	88,829
14/05/2018	68,000	84,663
21/05/2018	71,026	81,936
28/05/2018	87,739	83,096
04/06/2018	96,000	85,677
11/06/2018	86,361	85,814
18/06/2018	78,256	84,302
25/06/2018	91,052	85,652
02/07/2018	99,000	88,322
09/07/2018	91,550	88,967
16/07/2018	100,100	91,194
23/07/2018	94,000	91,755
30/07/2018	99,836	93,371
06/08/2018	109,484	96,594
13/08/2018	107,846	98,844
20/08/2018	107,482	100,572
27/08/2018	97,250	99,907

[v-shex-msft]

Hi @LijieWang ,

Nope, you can't use dax formula to do recursive calculation in power bi.

Regards,

Xiaoxin Sheng