1DateTime::Format::EpochU:s:eJrD(C3o)ntributed Perl DocumDeantteaTtiimoen::Format::Epoch::JD(3)
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NAME

6       DateTime::Format::Epoch::JD - Convert DateTimes to/from Julian Days
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SYNOPSIS

9         use DateTime::Format::Epoch::JD;
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11         my $dt = DateTime::Format::Epoch::JD->parse_datetime( 2453244.5 );
12          # 2004-08-27T00:00:00
13         DateTime::Format::Epoch::JD->format_datetime($dt);
14          # 2453244.5
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16         my $formatter = DateTime::Format::Epoch::JD->new();
17         my $dt2 = $formatter->parse_datetime( 2453244.5 );
18          # 2004-08-27T00:00:00
19         $formatter->format_datetime($dt2);
20          # 2453244.5
21

DESCRIPTION

23       This module can convert a DateTime object (or any object that can be
24       converted to a DateTime object) to the Julian Day number. This is the
25       number of days since noon U.T.C. on January 1, 4713 B.C. (Julian
26       calendar).
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28       This time scale was originally proposed by John Herschel, and is often
29       used in astronomical calculations.
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31       Similar modules are:
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33       •   DateTime::Format::Epoch::MJD
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35           Implements the "modified Julian Day", starting at midnight U.T.C.,
36           November 17, 1858.  This number is always 2,400,000.5 lower than
37           the JD, and this count only uses five digits to specify a date
38           between 1859 and about 2130.
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40       •   DateTime::Format::Epoch::RJD
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42           Implements the "reduced Julian Day", starting at noon U.T.C.,
43           November 16, 1858.  This number is always 2,400,000 lower than the
44           JD.
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46       •   DateTime::Format::Epoch::TJD
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48           Implements the "truncated Julian Day", starting at midnight U.T.C.,
49           May 24, 1968.  This number is always 2,440,000,5 lower than the JD.
50           Actually, there is another version of the TJD, defined as JD modulo
51           10,000.  But that one is a bit harder to implement, so you'll have
52           to do with this version of TJD.  Or don't use TJD's at all.
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54       •   DateTime::Format::Epoch::RataDie
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56           Implements the Rata Die count, starting at January 1, 1
57           (Gregorian).  This count is used by DateTime::Calendar programmers.
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59       •   DateTime::Format::Epoch::Lilian
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61           Implements the Lilian count, named after Aloysius Lilian (a 16th
62           century physician) and first used by IBM (a 19th century punched
63           card machine manufacturer).  This counts the number of days since
64           the adoption of the Gregorian calendar.  Only days are counted, and
65           October 15, 1584 is day 1.
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METHODS

68       Most of the methods are the same as those in DateTime::Format::Epoch.
69       The only difference is the constructor.
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71       •   new()
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73           Constructor of the formatter/parser object. It has no parameters.
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SUPPORT

76       Support for this module is provided via the datetime@perl.org email
77       list. See http://lists.perl.org/ for more details.
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AUTHOR

80       Eugene van der Pijll <pijll@gmx.net>
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83       Copyright (c) 2004 Eugene van der Pijll.  All rights reserved.  This
84       program is free software; you can redistribute it and/or modify it
85       under the same terms as Perl itself.
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SEE ALSO

88       DateTime
89
90       datetime@perl.org mailing list
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94perl v5.36.0                      2022-07-22    DateTime::Format::Epoch::JD(3)
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