Time::JulianDay(3)					User Contributed Perl Documentation					Time::JulianDay(3)

NAME

       Time::JulianDay -- Julian calendar manipulations

SYNOPSIS

	       use Time::JulianDay

	       $jd = julian_day($year, $month_1_to_12, $day)
	       $jd = local_julian_day($seconds_since_1970);
	       $jd = gm_julian_day($seconds_since_1970);
	       ($year, $month_1_to_12, $day) = inverse_julian_day($jd)
	       $dow = day_of_week($jd)

	       print (Sun,Mon,Tue,Wed,Thu,Fri,Sat)[$dow];

	       $seconds_since_jan_1_1970 = jd_secondslocal($jd, $hour, $min, $sec)
	       $seconds_since_jan_1_1970 = jd_secondsgm($jd, $hour, $min, $sec)
	       $seconds_since_jan_1_1970 = jd_timelocal($sec,$min,$hours,$mday,$month_0_to_11,$year)
	       $seconds_since_jan_1_1970 = jd_timegm($sec,$min,$hours,$mday,$month_0_to_11,$year)

DESCRIPTION

       JulianDay is a package that manipulates dates as number of days since some time a long time ago.  It's easy to add and subtract time using
       julian days...

       The day_of_week returned by day_of_week() is 0 for Sunday, and 6 for Saturday and everything else is in between.

ERRATA

       Time::JulianDay is not a correct implementation.  There are two problems.  The first problem is that Time::JulianDay only works with
       integers.  Julian Day can be fractional to represent time within a day.	If you call inverse_julian_day() with a non-integer time, it will
       often give you an incorrect result.

       The second problem is that Julian Days start at noon rather than midnight.  The julian_day() function returns results that are too large by
       0.5.

       What to do about these problems is currently open for debate.  I'm tempted to leave the current functions alone and add a second set with
       more accurate behavior.

       There is another implementation in Astro::Time that may be more accurate.

GENESIS

       Written by David Muir Sharnoff <muir@idiom.com> with help from previous work by Kurt Jaeger aka PI <zrzr0111@helpdesk.rus.uni-stuttgart.de>
	    based on postings from: Ian Miller <ian_m@cix.compulink.co.uk>; Gary Puckering <garyp%cognos.uucp@uunet.uu.net>	 based on
       Collected Algorithms of the ACM ?; and the unknown-to-me author of Time::Local.

LICENSE

       Copyright (C) 1996-1999 David Muir Sharnoff.  License hereby granted for anyone to use, modify or redistribute this module at their own
       risk.  Please feed useful changes back to muir@idiom.com.

perl v5.12.1							    2004-02-08							Time::JulianDay(3)