juliantojd
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
$timestamp = time()
] )
Diese Funktion konvertiert den in
timestamp übergebenen Wert (in Sekunden
seit dem 1.1.1970) in das entsprechende Julianische Datum. Wird
kein timestamp übergeben, so wird das
Julianische Datum des aktuellen Tages zurückgegeben.
Parameter-Liste
-
timestamp -
Ein zu konvertierender Unix Timestamp.
Rückgabewerte
Ein Julianischer Tag als Integer.
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User Contributed Notes
unixtojd - [7 notes]
hrabi at linuxwaves dot com ¶
6 years ago
hrabi at linuxwaves dot com ¶
6 years ago
This is unusable. Julian Day start at noon, not midnight. It's better to use Fabio solution (however there is a lurk problem with leap second).
<?php
function mmd($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 ¶
6 years ago
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.
Anonymous ¶
6 years ago
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;
johnston at capsaicin dot ca ¶
9 years ago
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 ¶
9 years ago
Remember that UNIX timestamps indicate a number of seconds from midnight of January 1, 1970 on the Gregorian calendar, not the Julian Calendar.
Anonymous ¶
1 year ago
Since upgrading from PHP 5.2.9 to 5.3.10, PHP is throwing the error:
... PHP Fatal error: Call to undefined function unixtojd() in .../unixtojd.php on line 5
Checking phpinfo(), I can see that the calendar lib is enabled:
'--enable-calendar=shared'
Searching on Google for posts since the first release of PHP 5.3 (June 30, 2009) did not reveal much more: http://goo.gl/2YbWj
If anyone has an answer, please notify me at lsiden at gmail since I have not found a way to get notified here.
Thank you!