(12C) Gregorian Date to Julian Day Number and vice versa

[Albert Chan]

(01-14-2019 12:54 PM)Dieter Wrote:  Example (assuming D.MY mode):

4,071979 [R/S] => 2444059
2444444  [R/S] => 23,071980

Perhaps calculation via Modified Julian Date Number is easier: https://www.hermetic.ch/cal_stud/jdn.htm

MJD = JD - 2,400,000.5 = (JD-0.5) - 24e5

Store date, Nov 16, 1858, to memory 0

Redo above examples:

RCL 0 4.071979 ΔDYS ==> 44059

RCL 0 44444 DATE ==> 23,07,1980 3

Edit: stored date were off by 1, to compensate for rounded-up JD
Officially, MJD(Nov 17, 1858, 00:00:00) = 0

17.111858 Enter 4.071979 ΔDYS
=> 44058 MJD
=> 2444058.5 JD, rounded-up to 2444059