How to write M Language for flagging previous year last day of year

[Niels_T]

Hello

I have a day of the year column (01 - 365 or 01 - 366) and I was wondering how to get the last day of the year get of the PREVIOUS year get flagged as "Previous year". 

Basically like this pseudo code:

if (previous year) [day of the year] = 365 or (previous year) [day of the year] = 366 then "Previous Year" else null

[amitchandak · Accepted solution]

@Niels_T , Last day of previous year

Date.EndOfYear(Date.AddYears([date], -1))

If date is in previous year

Date.IsInPreviousYear([Date])