day of year from Igor dateTime object

You could use something like this:

function DayOfYear()
	
	string strdate=Secs2Date(DateTime,-2)
	variable yyyy=str2num(StringFromList(0, strdate,"-"))
	variable mm=str2num(StringFromList(1, strdate,"-"))
	variable dd=str2num(StringFromList(2, strdate,"-"))
	
	return dateToJulian(yyyy, mm, dd) - dateToJulian(yyyy, 1, 1) + 1
end

or this

function DayOfYear(secs)
	variable secs
	
	variable yyyy, mm, dd
	sscanf Secs2Date(secs,-2), "%g-%g-%g", yyyy, mm, dd

	return dateToJulian(yyyy, mm, dd)-dateToJulian(yyyy, 1, 1)+1
end

I know it is late, but thank you for this :)