jdtounix
(PHP 4, PHP 5)
jdtounix — Convert Julian Day to Unix timestamp
Описание
int jdtounix
( int $jday
)
This function will return a Unix timestamp corresponding to the Julian Day given in jday or FALSE if jday is not inside the Unix epoch (Gregorian years between 1970 and 2037 or 2440588 <= jday <= 2465342 ). The time returned is localtime (and not GMT).
Список параметров
- jday
-
A julian day number between 2440588 and 2465342.
Возвращаемые значения
The unix timestamp for the start of the given julian day.
Коментарии
Remember that UNIX timestamps indicate a number of seconds from midnight of January 1, 1970 on the Gregorian calendar, not the Julian Calendar.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.
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!!
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
unixtojd() assumes that your timestamp is in GMT, but jdtounix() returns a timestamp in localtime.so
<?php
$d1=jdtogregorian(unixtojd(time()));
$d2= gmdate("m/d/Y");
$d3=date("m/d/Y");
?>
$d1 always equals $d2 but $d1 may differ from $d3