Re: [boost] gregorian::date limited to years 1400 - 9999

Subject: Re: [boost] gregorian::date limited to years 1400 - 9999
From: Oswin Krause (Oswin.Krause_at_[hidden])
Date: 2016-12-23 04:58:35

On 2016-12-23 10:29, alanbirtles2 wrote:
> The lower limit is more or less explained in the documentation
> http://www.boost.org/doc/libs/1_62_0/doc/html/date_time/gregorian.html
> 
>> The implemented calendar is a "proleptic Gregorian calendar" which 
>> extends
>> dates back prior to the Gregorian Calendar's first adoption in 1582. 
>> The
>> current implementation supports dates in the range 1400-Jan-01 to
>> 9999-Dec-31. Many references will represent dates prior to 1582 using 
>> the
>> Julian Calendar, so caution is in order if accurate calculations are
>> required on historic dates. See Calendrical Calculations by Reingold &
>> Dershowitz for more details. Date information from Calendrical
>> Calculations has been used to cross-test the correctness of the 
>> Gregorian
>> calendar implementation.
> 
Hi,

No, this is not an answer to the question. The documentation explains 
that one has to be cautious with dates prior to 1582 but it does not 
explain why the earliest date supported is 1400 and not for example 0. I 
am also curious why this is the case.