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 <cpan@dave.sharnoff.org> 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
       cpan@dave.sharnoff.org.