Excel should support DAYOFYEAR(year,month,day) returns julian dat.
 

And the reverse function JULDATE. This is easier than writing the equation:
=DATE(2005,4,15)-DATE(2005,1,1)+1

While complaining about lack of basic essential
functionality in Excel is OK, it should be accompanied by
some type of Excel-related question. Posts that simply
whine waste everyone's time. In addition to your
complaint, you could have asked "Is there a shorter
alternative to my formula?" Sure! A UDF!

Function Dayofyear(iYear As Long, _
iMonth As Long, iDay As Long) As Long
Dayofyear = DateSerial(iYear, iMonth, iDay) - _
DateSerial(iYear, 1, 1) + 1
End Function

HTH
Jason
Atlanta, GA

-----Original Message-----
And the reverse function JULDATE. This is easier than
writing the equation:
=DATE(2005,4,15)-DATE(2005,1,1)+1
.