The week date is a date identified by calendar week and day numbers.
The calendar week is a seven day period within a calendar year,
starting on a Monday and identified by its ordinal number within the
year; the first calendar week of the year is the one that includes the
first Thursday of that year. In the Gregorian calendar, this is
equivalent to the week which includes January 4.
The Julian day number is in elapsed days since noon (Greenwich mean
time) on January 1, 4713 BCE (in the Julian calendar).
In this document, the astronomical Julian day number is same as the
original Julian day number. And the chronological Julian day number
is a variation of the Julian day number. Its days begin at midnight
on local time.
In this document, when the term "Julian day number" simply appears, it
just refers to "chronological Julian day number", not the original.
The modified Julian day number is in elapsed days since midnight
(Coordinated universal time) on November 17, 1858 CE (in the Gregorian
calendar).
In this document, the astronomical modified Julian day number is same
as the original modified Julian day number. And the chronological
modified Julian day number is a variation of the modified Julian day
number. Its days begin at midnight on local time.
In this document, when the term "modified Julian day number" simply
appears, it just refers to "chronological modified Julian day number",
not the original.
Creates a date object denoting the given calendar date.
In this class, BCE years are counted astronomically.
Thus, the year before the year 1 is the year zero,
and the year preceding the year zero is the year -1.
The month and the day of month should be a negative or a positive number
(reverse order when negative).
They should not be zero.
The last argument should be a Julian day number
which denotes the first day of the Gregorian calendar.
You can also give true which mean the proleptic Gregorian calendar,
and false which mean the proleptic Julian calendar.
Default is Date::ITALY (October 15, 1582).
Parses the given representation of dates and times,
and creates a date object.
If the optional second argument is true and
the detected year is in the range 0 to 99,
considers the year a 2-digit form and makes it full.
Default is false.
_parse is also available.
This method is similar to parse,
but returns a hash which contain detected elements,
not creates a date object.
Returns the difference between the two dates if the x is a date object.
If the x is a numeric value, it returns
a date object pointing x days before self.
Parses the given representation of dates and times,
and returns an array which contain detected elements
(year, month, day of month, hour, minute, second, timezone and day of week).
If the optional second argument is true and
the detected year is in the range 0 to 99,
considers the year a 2-digit form and makes it full.
Default is false.