Read Wikipedia article computus
On 18 Nov 2008, at 13:42, Nathan Rixham wrote:
Nathan Rixham wrote:
Kevin Waterson wrote:
This one time, at band camp, tedd <[EMAIL PROTECTED]> wrote:
Easter lands on different dates depending upon several different
factors. For example in Canada it's the day after it is in the
USA -- I guess Canadians are slower, eh? :-)
Also, in some religions the date is the full-moon after the
Equinox and not a specific date. Furthermore, the Equinox does
not always land on March 21, but sometimes it's March 20 (leap
year).
So, the key is to find the date of the Vernal Equinox, which as
you say,
does not always land on March 21. However, every 400 years, it
does happen
on March 21 7:30am GST. From there, we can derive a base for
future dates.
Every 4th year is a leap year, and every 4th century, giving 97
leap days
each 400 years. so (365*400+97)/400 is 365.2425 gives the length
of each year.
Then the dates can be calculated as follows:
http://phpro.org/examples/Get-Vernal-Equinox.html
Any improvements welcomed
Kind regards
Kevin
just for the sake of madness, many moons ago I wrote this bit of
code which will create a "datestamp"
1st January 1 (datestamp 1) to 31st December 32767 (datestamp
11967900)
datestamp(year,month,day)
Turns any date in the valid date range into an integer value
datestamp_parts(datestamp)
Takes input datestamp and returns an array containing the date
info */
function datestamp($y=0,$m=0,$d=0) {
/*
datestamp(year, month, day)
year INT | not required | default: current year
month INT | not required | default: current month
day INT | not required | default: current day
called with no values returns the current dates datestamp
returns false on error
*/
$datestamp = false;
$y = $y ? $y : date("Y");
$m = $m ? $m : date("n");
$d = $d ? $d : date("j");
if(checkdate($m, $d, $y)) {
$datestamp = ((($y-1)*365)+date("z",mktime(1,1,1,$m,$d,2007))
+(floor($y/4)-(floor($y/100)-floor($y/400+1;
if(floor($y/100) == $y/100) && (floor($y/400) == $y/400))) ||
((floor($y/4) == $y/4) && (floor($y/400) == $y/400)) || ((floor($y/
4) == ($y/4)) && !(floor($y/100) == $y/100))) &&
(date("z",mktime(1,1,1,$m,$d,2000))<60)) {
$datestamp--; //leapyear adjustment
}
}
return $datestamp;
}
function datestamp_parts($datestamp=0) {
if($datestamp && ($datestamp < 11967900)) {
$yd= ((365)+($datestamp-((ceil(($datestamp-
((floor((($datestamp/365)/4)-floor(($datestamp/365)/
100)+floor(($datestamp/365)/400)/365))*(365-
(floor(((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/
365))-1)/4)-(floor(((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/
365))-1)/100)-floor(((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/
365))-1)/400))); $y = (ceil(($datestamp-
((floor((($datestamp/365)/4)-floor(($datestamp/365)/
100)+floor(($datestamp/365)/400)/365)); $l =
((floor((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/365))/
4)-(floor((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/365))/
100)-floor((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/365))/
400)))-(floor(((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/
365))-1)/4)-(floor(((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/
365))-1)/100)-floor(((ceil(($datestamp-((floor((($datestamp/365)/4)-
floor(($datestamp/365)/100)+floor(($datestamp/365)/400)/
365))-1)/400; if((!$l && $yd>365)) {
$yd=$yd-365;
$y++;
$l=1;
} elseif($l && $yd>366) {
$yd=$yd-366;
$y++;
$l=0;
}
$uy = $l ? 2000 : 2001;
$m = date("n",mktime(1,1,1,1,$yd,$uy));
$md = date("j",mktime(1,1,1,1,$yd,$uy));
$out['year'] = $y;
$out['month'] = $m;
$out['month_day'] = $md;
$out['leapyear'] = $l;
$out['year_day'] = $yd;
return $out;
} else {
return false;
}
}
?>
not sure why I'm throwing it in but it sure was interesting trying
to make it, possibly the single longest line of eye watering code
ever in there lol!
after more reflection, this should be a task on celebrity php code
challenge "refactor that"
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