// JavaScript Document
<!-- zobrazenie aktualneho JD
//---------------------------------------------------------
//(algoritmus pre Juliánsky dátum prevzatý od Press a kol.)
//---------------------------------------------------------
function show_jd()
{
    var numdays = new Array(31,28,31,30,31,30,31,31,30,31,30,31);
	var jy, ja, jm;			// pomocne

    var today = new Date();

    var year = today.getYear();
    if( year < 2000 ) year += 1900;
    if( year < 2000 ) year += 100;  // Netscape 3 a IE 4.7 vracajú 0 namiesto 100 pre 2000
    var month = today.getMonth()+1;
    var day   = today.getDate();
    var hour  = today.getHours();
    var mins  = today.getMinutes();
    var secs  = today.getSeconds();

    // prevedie na UT
    var TZ = today.getTimezoneOffset()/60;
    hour += TZ;

    // kontrola pretecenia do susedneho dna
    if( hour >= 24 ) {
        hour -= 24;
        ++day;
        if( day > numdays[month-1] ) {
            day = 1;
            ++month;
            if( month > 11 ) {
                month -= 12;
                ++year;
            }
        }
    }

    // kontrola pretecenia do minuleho dna
    if( hour < 0 ) {
        hour += 24;
        --day;
        if( day < 1 ) {
            day = numdays[month-1];
            --month;
            if( month < 1 ) {
                month += 12;
                --year;
            }
        }
    }

    // zaciatok vypoctu JD
	if( month > 2 ) {
		jy = year;
		jm = month + 1;
	} else {
		jy = year - 1;
		jm = month + 13;
	}

	var intgr = Math.floor( Math.floor(365.25*jy) + Math.floor(30.6001*jm) + day + 1720995 );

	// overuje prepnutie na Gregoriansky kalendar
    var gregcal = 15 + 31*( 10 + 12*1582 );
	if( day + 31*(month + 12*year) >= gregcal ) {
		ja = Math.floor(0.01*jy);
		intgr += 2 - ja + Math.floor(0.25*ja);
	}

	// upravuje rozdiel o polden
	var dayfrac = hour/24.0 - 0.5;
	if( dayfrac < 0.0 ) {
		dayfrac += 1.0;
		--intgr;
	}

	// teraz nastavi zlomok dna
	var frac = dayfrac + (mins + secs/60.0)/60.0/24.0;

    // zaokruhli na cele sekundy
    var jd0 = (intgr + frac)*1000;
    var jd  = Math.floor(jd0);
    if( jd0 - jd > 0.5 ) ++jd;
    document.write(jd/1000);
}
// koniec predpisu -->