unixtojd

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.

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;

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";        break;    }    $t_unixtojd += $time2 - $time1;    $t_fast_unixtojd += $time3 - $time2;}echo "unixtojd: $t_unixtojd sec\nfast_unixtojd: $t_fast_unixtojd sec\n";unixtojd: 0.42854166030884 secfast_unixtojd: 0.13218021392822 sec

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 :-).

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).<?phpfunction 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)?>referenceunix time, and UTC, TAI, ntp, ... problems: http://en.wikipedia.org/wiki/Unix_timeJulian Date Converter: http://aa.usno.navy.mil/data/docs/JulianDate.htmlhistory overview: http://parris.josh.com.au/humour/work/17Nov1858.shtml

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.