WP34s: date functions and negative years

[walter b]

(01-18-2015 01:01 AM)Paul Dale Wrote:  What we have now is correct as per the documentation -- it is quite explicite that dates before 8AD can be wrong.

For sake of completeness, please let me quote footnote 33 of the WP 31S manual:

"Calculation of weekdays for the past depends on the calendars used at that time – there may be different true results for different countries depending on the date the particular country introduced the Gregorian calendar. Officially, that calendar became effective in October 1582 in the catholic world. Many countries switched not earlier than in 1752, others joined even later (until 1949). See the commands JG1582 and JG1752 taking care of most cases. Note, however, there are still also other calendars in use on this planet, e.g. in the Muslim world.
Dates before the year 8 A.D. may be indicated differently than they were at that time due to the inconsistent application of the leap year rule before then. We count on your understanding and hope this shortcoming will not affect too many calculations.
Note that 8 A.D. should be better written A.D. 8 or even A.D. VIII correctly – quite some false Latin is found in the English language. Nobody, however, counted years this way at that time – around the Mediterranean Sea, it was the year DCCLXI A.V.C. then. Also note the Julian calendar was introduced and became valid not earlier than DCCVIII A.V.C. – before, months were organized differently. Julius Caesar was murdered in DCCIX A.V.C., just one year later; calendars may be a sensitive topic."

(01-18-2015 01:01 AM)Paul Dale Wrote:  

1. The calendar was bizarre before about 8AD, I could put a break there and force an error.
2. The Julian calendar was only introduced late BC, we could break there and live with being incorrect until 8AD, again with an error before.
3. We could lie and pretend the Julian calendar went backwards before its creation to the origin of the Julian day number reference.
   

I tend to vote for 1 or 3. 1 would be a clean solution. 3 would allow for calculating weekdays for all recorded events in history of mankind. Though I don't know yet how far back a seven-day week was used and where.

d:-?