Talk:Calendar: Difference between revisions

Maybe a the switch over date should be an argument, defaulting to the British date of switch? I am also a bit curious as to what dating system the [[wp:International Astronomical Union|International Astronomical Union]] use. Maybe there is standard for year/date definitions in [[wp:Common_Era|BCE and CE]]?

:: The IAU uses the Gregorian calendar proleptically even for dates long before its inception. (Many of the dates they deal with are so far in the past that the difference between the introductions of the Julian and Gregorian calendars is a tiny fraction of time, relatively.) They also generally don't use BCE dates, instead continuing the CE era backward into 0 and negative numbers (so 1 BCE is 0 CE, 2 BCE is -1 CE, etc.) --~~

 

Or... Another task could be to calculate the locale date and time, based on latitude, longitude, (altitude?) AND date. Ouch... to tough for me.

 

:Conceptually, this would require a data structure which may be conceptualized as database table where the primary key was a polygon (a country's polygon) and a time interval (a time interval where that polygon defines that country's boundary). The table would also have to have a bit which indicates whether that time interval and polygon corresponds to the Julian or Gregorian calendar. All that you have to do to populate this table is find a list of all country boundaries as latitude/longitude polygons as well as how that has changed with each war or treaty settlement that has changed a country's boundary. And note that the algorithm which uses this data structure might have to return multiple values (when a border was in dispute during a region of time where one side of the border was Gregorian and the other side was Julian). An issue, of course, is that historical country boundaries might not always exactly correspond to anything we can currently unambiguously assign a latitude and longitude to (for example: when a river was the boundary -- rivers are wide and can move somewhat over the course of a century). On the other hand, this data structure can be considerably simplified where both sides of a border were using the same calendar. Nevertheless, I am not aware of any such list, and I think that this sounds like a huge historical research project. But the programming itself sounds relatively trivial (at least in comparison). --[[User:Rdm|Rdm]] 18:44, 6 June 2011 (UTC)

 

== Improving the task description ==