Calandar continuity
The day after Julian 4th of Oct 1582 is NOT the 5th !
It's the Gregorian 15th of Oct 1582.
- From year BCE 42 to 4th of Oct 1582, we use the Julian calandar.
- Before, we use the proleptic Julian calendar
- After, we use the gregorian calandar (nowadays we use gregorian).
- You can use proleptic julian calander AFTER 1582-Oct-4, this overlap the gregorian cal.
Officialy there are no 1582-Oct-5(Julian), but RPNenh allow you to enter such proleptic date, and it will be automatically translated into correct gregorian date.
Ex.: {1582 10 5} ListJ->DT will give <GR 1582-10-15 0:0:0>. If you want to display it as a proleptic date, use >JUL, it will displayed as <JUL 1582–10–5 0:0:0 >.
Date system
Internally all dates are stored as Julian Day number (JD).
Everything else is just displaying,
when you see <GR 2003-12-31 0:0:0 > in fact RPNe handle the number 2453004.5, and display the way you want when you use >JD>CAL>JUL.
That the raison you can compute difference between two date even if format is not the same :
Ex.: <JD 2453054.5> <GR 2003-12-31 0:0:0 > - gives 50