GregorianToJD

Description

int gregoriantojd ( int month, int day, int year )

Valid Range for Gregorian Calendar 4714 B.C. to 9999 A.D.

Although this function can handle dates all the way back to 4714 B.C., such use may not be meaningful. The Gregorian calendar was not instituted until October 15, 1582 (or October 5, 1582 in the Julian calendar). Some countries did not accept it until much later. For example, Britain converted in 1752, The USSR in 1918 and Greece in 1923. Most European countries used the Julian calendar prior to the Gregorian.
例子 1. Calendar functions
<?php $jd = GregorianToJD(10, 11, 1970); echo "$jd\n"; $gregorian = JDToGregorian($jd); echo "$gregorian\n"; ?>

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ryker at ridgex dot net
06-Jun-2006 11:27


/*

* ComputeDateDifference(...)

*   Description:

*     Calculates the difference between two dates.

*

*   Parameter:

*     $m0, $d0, $y0   => 1. Moth/Day/Year

*     $m1, $d1, $y1   => 2. Moth/Day/Year

*

*   Return:

*     Difference between given dates in days.

*

*   Autor:

*     06.06.2006 - Christian Meyer <ryker@ridgex.net>

*/

function ComputeDateDifference($m0,$d0,$y0,$m1,$d1,$y1)

{

  $x0 = gregoriantojd($m0,$d0,$y0);

  $x1 = gregoriantojd($m1,$d1,$y1);  

  

  $diff = $x1 - $x0;

  

  if ($diff < 0)

    $diff *= -1; // abs

    

  return $diff;    

}

jettyrat at jettyfishing dot com
18-Mar-2005 05:34


You can obtain the decimal fraction of the Julian date with the php gregoriantojd() function or the function shown below by applying this code to the returned value.



  $julianDate = gregoriantojd($month, $day, $year);



  //correct for half-day offset

  $dayfrac = date('G') / 24 - .5;

  if ($dayfrac < 0) $dayfrac += 1;



  //now set the fraction of a day

  $frac = $dayfrac + (date('i') + date('s') / 60) / 60 / 24;



  $julianDate = $julianDate + $frac;

httpwebwitch
09-Jun-2004 07:04


This function also ignores decimal fractions in JD dates, and it uses non-standard format for returning the Gregorian date. 



So, if your JD date is 2453056.28673, the Gregorian returned value is 2/20/2004, not "2004-02-20 23:45:36"



The decimal part is important, since the Julian day begins at noon, for example 2453056.49 is on Friday, 2453056.50 is on Saturday. Discarding the decimal part means that your returned Gregorian Date will be wrong 50% of the time.

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