Calendar Funktionen
according to http://www.decimaltime.hynes.net/dates.html#jd and reading "X. Calendar Functions" on this side, it seems that php "jd" is precisely mean as "Chronological Julian Day" (should it be named cjd, and primarily strictly mentioned - isn't it?), used for covnersion between calendar systems. Than it's ok (but Incomplete manual is strongly confusing here IMHO).
Even that, cJD is adjusted to a local time, so... I am rather babeled now, so nothing else :-).
unixtojd
(PHP 4, PHP 5)
unixtojd — Konvertiert Unix-Timestamp in Julianisches Datum
Beschreibung
int unixtojd
([ int $timestamp
] )
Diese Funktion konvertiert den in timestamp übergebenen Wert (in Sekunden seit dem 1.1.1970) in das entsprechende Julianische Datum. Wird kein timestamp übergeben, so wird das Julianische Datum des aktuellen Tages zurückgegeben.
Parameter-Liste
- timestamp
-
Ein zu konvertierender Unix Timestamp.
Rückgabewerte
Ein Julianischer Tag als Integer.
add a note
User Contributed Notesunixtojd
hrabi at linuxwaves dot com
29-Mar-2007 07:02
29-Mar-2007 07:02
hrabi at linuxwaves dot com
29-Mar-2007 04:33
29-Mar-2007 04:33
This is unusable. Julian Day start at noon, not midnight. It's better to use Fabio solution (however there is a lurk problem with leap second).
<?php
function mmd($txt, $str_time) {
$t = strtotime($str_time);
$j = unixtojd($t);
$s = gmstrftime('%D %T %Z', $t);
$j_fabio = $t / 86400 + 2440587.5;
printf("${txt} => (%s) %s, %s U, %s J, or %s J<br>\n", $str_time, $s, $t, $j, $j_fabio);
}
//$xt = strtotime("1.1.1970 15:00.00 GMT");
$sam = "9.10.1995 02:00.01 GMT";
$spm = "9.10.1995 22:00.01 GMT";
// unixtojd for $spm returns 2450000 (OK), but for $sam returns 2450000 too! (it is wrong).
mmd("am", $sam); // should be 2449999 (+ 0.58334)
mmd("pm", $spm); // should be 2450000 (+ 0.41668)
?>
reference
unix time, and UTC, TAI, ntp, ... problems: http://en.wikipedia.org/wiki/Unix_time
Julian Date Converter: http://aa.usno.navy.mil/data/docs/JulianDate.html
history overview: http://parris.josh.com.au/humour/work/17Nov1858.shtml
fabio at llgp dot org
31-Aug-2006 02:09
31-Aug-2006 02:09
If you need an easy way to convert an unix timestamp to a decimal julian day you can use:
$julianDay = $unixTimeStamp / 86400 + 2440587.5;
86400 is the number of seconds in a day;
2440587.5 is the julian day at 1/1/1970 0:00 UTC.
10-Aug-2006 07:22
Its clearly stated that this function returns the Julian Day, not Julian Day + time.
If you want the time with it you will have to do something like:
$t=time();
$jd=unixtojd($t)+($t%60*60*24)/60*60*24;
warhog at warhog d0t net
12-Jul-2005 02:11
12-Jul-2005 02:11
Well, that's neither a bug, nor an interesting quirk.. The explanation is quite simple:
The Integer containing a julian date (jd) only stores the date, not the time. When you convert a unix-timestamp, which stores also the time, into a jd, the time-information won't be transferred into the jd. When converting back the jd into a unix-timestamp, you'll get a timestamp for the specific day at 2 o'clock am. ( 02:00:00 )
Sample:
Timestamp: 1121206013
JD: 2453565
Timestamp from JD: 1121212800
Original Timestamp "d.m.y H:i:s": 13.07.2005 00:06:53
Timstamp from JD "d.m.y H:i:s": 13.07.2005 02:00:00
greetz
Mike
21-Dec-2004 08:57
21-Dec-2004 08:57
Interesting quirk ... maybe bug.
If you use today = unixtojd(time())
then use jdtounix(today) the result is one day short of today.
johnston at capsaicin dot ca
19-Nov-2003 01:43
19-Nov-2003 01:43
Also note that epoch is in UTC time (epoch is a specific point in time - epoch is not different for every time zone), so be aware of timezone complexities.
pipian at pipian dot com
12-Jun-2003 09:29
12-Jun-2003 09:29
Remember that UNIX timestamps indicate a number of seconds from midnight of January 1, 1970 on the Gregorian calendar, not the Julian Calendar.