SQL Server function to convert datetime to julian day

CREATE FUNCTION dbo.DateToJulian(@InDate datetime)
RETURNS numeric(18,0)
AS
BEGIN
DECLARE @numJulDate numeric(18,0)

IF (convert(char(2),@InDate,2) > 30 AND convert(char(2),@InDate,2) <= 99)
BEGIN
set @numJulDate = cast(convert(char(2),@InDate,2) + (replicate('0', 3 - len(convert( char(3), datepart(dayofyear, @InDate)))) + convert( char(3), datepart(dayofyear, @InDate))) AS numeric(18,0))
END
ELSE
set @numJulDate = cast('1' + convert(char(2),@InDate,2) + (replicate('0', 3 - len(convert( char(3), datepart(dayofyear, @InDate)))) + convert( char(3), datepart(dayofyear, @InDate))) AS numeric(18,0))

RETURN @numJulDate
END