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unixtojd Переводит метку времени Unix в юлианский день


unixtojd(?int $timestamp = null): int|false

Возвращает юлианский день для заданной метки времени Unix timestamp (количество секунд с 1.1.1970) либо для текущего времени, если аргумент timestamp не задан. В любом случае, время рассматривается как местное время (не UTC).

Список параметров


Метка времени Unix для преобразования.

Возвращаемые значения

Число дней в юлианском летоисчислении или false, если возникла ошибка.

Список изменений

Версия Описание
8.0.0 timestamp теперь допускает значение null.

Смотрите также

  • jdtounix() - Переводит число дней в юлианском летоисчислении в метку времени Unix

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User Contributed Notes 6 notes

fabio at llgp dot org
17 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.
17 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:

unixtojd at isslow dot com
3 months ago
unixtojd is slow.
Direct arithmetics calculations are faster and still coherent with original unixtojd.

Feel free to add a test on $timestamp to set it to time() when $timestamp is null.

function fast_unixtojd($timestamp){
return intval($timestamp / 86400 + 2440588);

$time = time();
$t_unixtojd = 0;
$t_fast_unixtojd = 0;
for ($t = $time - 240 * 3600; $t < $time; $t++) {
$time1 = microtime(true);
$a = unixtojd($t);
$time2 = microtime(true);
$b = fast_unixtojd($t);
$time3 = microtime(true);
if ($a != $b) {
echo "$a $b $t\n";
$t_unixtojd += $time2 - $time1;
$t_fast_unixtojd += $time3 - $time2;
echo "unixtojd: $t_unixtojd sec\nfast_unixtojd: $t_fast_unixtojd sec\n";

unixtojd: 0.42854166030884 sec
fast_unixtojd: 0.13218021392822 sec
hrabi at linuxwaves dot com
17 years ago
according to 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 :-).
hrabi at linuxwaves dot com
17 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).

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)

unix time, and UTC, TAI, ntp, ... problems:
Julian Date Converter:
history overview:
johnston at capsaicin dot ca
20 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.
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