jdtounix

(PHP 4, PHP 5)

jdtounix — Jülyen Gün Sayısını, Unix zaman damgasına çevirir

Açıklama

int jdtounix ( int $julyengunu )

İşlev julyengunu'ne karşılık gelen Unix zaman damgasını ya da verilen julyengunu Unix zaman damgası aralığında (1970 ve 2037 Gregoryen yılları arası veya 2440588 <= julyengunu <= 2465342 ) değilse FALSE değerini döner. İşlevden dönen zaman damgası, GMT'ye göre değil, yerel zamana göredir.

Değiştirgeler

julyengunu: 2440588 ve 2465342 aralığında Jülyen Gün Sayısı.

Dönen Değerler

Jülyen Gün Sayısına, karşılık gelen Unix zaman damgası.

Ayrıca Bakınız

unixtojd() - Unix zaman damgasını, Jülyen Gün Sayısına çevirir

JewishToJD

JDToJulian

[edit] Last updated: Fri, 23 Mar 2012

add a note User Contributed Notes jdtounix

hrabi at linuxwaves dot com 29-Mar-2007 01:16


Beware, jd here is not (astronomical or geocentric) Julian Day (JD), but Chronological Julian Day (CJD)! When JD start at noon of UTC time (12:00 UTC), CJD start at midnight at *local* time! Or considering head "Chronlogical Julian Day/Date" at "http://www.decimaltime.hynes.net/dates.html", when day localy start (it should be at sunset for instance).



try this...

<?php

define("UJD", 2440587.5);

define("SEC4DAY", 86400);



function u2j($tm) {

   return $tm / SEC4DAY + UJD;

}



function mmd($txt, $str_time) {

   $t = strtotime($str_time);

   $j = unixtojd($t);

   $j_fabio = u2j($t);

   $s = strftime('%D %T %Z', $t);



   printf("${txt} => %s, CJD: %s, JD: %s<br>\n", $s, $j, $j_fabio);

}



$xt = strtotime("1.1.1970 0:00.00 GMT");

$slb = "-1 day 23:30"; // let CJD be N

$sla = "0:30.00"; // should be N+1

$slm = "0:00"; // should be N+1

$sgmt = "0:00.00 GMT"; // don't forget to observe JD.



mmd("local before", $slb);

mmd("local after", $sla);

mmd("local midnight", $slm);

mmd("GMT midnight", $sgmt);

?>



I got this (you see, JD havn't change day, because UTC noon is far away):

local before => 03/28/07 23:30:00 CEST, CJD: 2454188, JD: 2454188.39583

local after => 03/29/07 00:30:00 CEST, CJD: 2454189, JD: 2454188.4375

local midnight => 03/29/07 00:00:00 CEST, CJD: 2454189, JD: 2454188.41667

GMT midnight => 03/29/07 02:00:00 CEST, CJD: 2454189, JD: 2454188.5

erelsgl dot NOSPAM at cs dot technion dot ac dot il 19-Sep-2006 12:31


Just to clarify the differences between the different methods to convert a date to a timestamp.



Suppose:



<?php

$x = JDToUnix(GregorianToJD(9,23,2006));

$y = strtotime('2006-09-23');

$z = (GregorianToJD(9,23,2006) - 2440587.5) * 86400;

?>



Then, on a machine whoze timezone is GMT-0400, we get the following results:

<?php

$x === 1158969600;

$y === 1158984000;  //  $x + 4 hours

$z === 1159012800;  //  $x + 12 hours

?>

fabio at llgp dot org 30-Aug-2006 08:14


If you need an easy way to convert a decimal julian day to an unix timestamp you can use:



$unixTimeStamp = ($julianDay - 2440587.5) * 86400;



2440587.5 is the julian day at 1/1/1970 0:00 UTC

86400 is the number of seconds in a day

26-Jan-2005 11:50


Warning: the calender functions involving julian day operations seem to ignore the decimal part of the julian day count.



This means that the returned date is wrong 50% of the time, since a julian day starts at decimal .5 .  Take care!!

seb at carbonauts dot com 21-Oct-2003 06:10


Remember that unixtojd() assumes your timestamp is in GMT, but jdtounix() returns a timestamp in localtime.



This fooled me a few times.  



So if you have:



$timestamp1 = time();

$timestamp2 = jdtounix(unixtojd($timestamp1));



Unless your localtime is the same as GMT, $timestamp1 will not equal $timestamp2.

pipian at pipian dot com 12-Jun-2003 03:29


Remember that UNIX timestamps indicate a number of seconds from midnight of January 1, 1970 on the Gregorian calendar, not the Julian Calendar.

add a note