[Tdg] julian dates

[Rama Hoetzlein]

Check it out..

Julian Dates: http://aa.usno.navy.mil/data/docs/JulianDate.html

This is one of the "better" Julian Dates calculator online. It works for 
BCE years, leap years, and far into the future. Algorithm based on 
Numerical Recipes in C (ch 1.1, p.11-14). It is also the US Naval 
Observatory site so you'd think it'd be good.

If you enter March 1st, 2100 you get JD: 2488128.5
If you enter Feb 29th, 2100 you also get JD: 2488128.5
If you do the reverse from 2488128.5 you get: Feb 29th, 2100
If you do the reverse from 2488129.5 you get: Mar 2nd, 2100

In other words, on these years (1600, 1700, 1900, 2100, etc.) there >is< 
no March 1st.
This is problematic because it implies that it is not possible to 
represent March 1st dates on century years after 1600.

Who needs these date anyway..

Feel free to test your favorite Julian Date calculator with this.
I can't find another JD algorithm that doesn't fail the test.

-R