jp.co.isic.SwissEphemeris
クラス SweDate
java.lang.Object
jp.co.isic.SwissEphemeris.SweDate
- public class SweDate
- extends Object
メソッドの概要 |
static int |
swe_date_conversion(int y,
int m,
int d,
double uttime,
char c,
double[] tjd)
Describe swe_date_conversion method here. |
static double |
swe_julday(int year,
int month,
int day,
double hour,
int gregflag)
swe_julday method.
|
static void |
swe_revjul(double jd,
int gregflag,
int[] jyear,
int[] jmon,
int[] jday,
double[] jut)
Describe swe_revjul method here.
|
SweDate
public SweDate()
swe_date_conversion
public static int swe_date_conversion(int y,
int m,
int d,
double uttime,
char c,
double[] tjd)
- Describe
swe_date_conversion
method here.
- パラメータ:
y
- an int
year valuem
- an int
month valued
- an int
day valuec
- a char
calendar g[regorian]|j[ulian]|a[stro = greg]
- 戻り値:
- an
int
value
swe_julday
public static double swe_julday(int year,
int month,
int day,
double hour,
int gregflag)
swe_julday
method.
This function returns the absolute Julian day number (JD)
for a given calendar date.
The arguments are a calendar date: day, month, year as integers,
hour as double with decimal fraction.
If gregflag = SE_GREG_CAL (1), Gregorian calendar is assumed,
if gregflag = SE_JUL_CAL (0),Julian calendar is assumed.
The Julian day number is system of numbering all days continously
within the time range of known human history. It should be familiar
for every astrological or astronomical programmer. The time variable
in astronomical theories is usually expressed in Julian days or
Julian centuries (36525 days per century) relative to some start day;
the start day is called 'the epoch'.
The Julian day number is a double representing the number of
days since JD = 0.0 on 1 Jan -4712, 12:00 noon.
Midnight has always a JD with fraction .5, because traditionally
the astronomical day started at noon. This was practical because
then there was no change of date during a night at the telescope.
From this comes also the fact the noon ephemerides were printed
before midnight ephemerides were introduced early in the 20th century.
NOTE: The Julian day number is named after the monk Julianus. It must
not be confused with the Julian calendar system, which is named after
Julius Cesar, the Roman politician who introduced this calendar.
The Julian century is named after Cesar, i.e. a century in the Julian
calendar. The 'gregorian' century has a variable lenght.
Be aware the we always use astronomical year numbering for the years
before Christ, not the historical year numbering.
Astronomical years are done with negative numbers, historical
years with indicators BC or BCE (before common era).
Year 0 (astronomical) = 1 BC
year -1 (astronomical) = 2 BC
etc.
Original author: Marc Pottenger, Los Angeles.
with bug fix for year < -4711 15-aug-88 by Alois Treindl
(The parameter sequence m,d,y still indicates the US origin,
be careful because the similar function date_conversion() uses
other parameter sequence and also Astrodienst relative juldate.)
References: Oliver Montenbruck, Grundlagen der Ephemeridenrechnung,
Verlag Sterne und Weltraum (1987), p.49 ff
related functions: swe_revjul() reverse Julian day number:
compute the calendar date from a given JD
date_conversion() includes test for legal date values
and notfies errors like 32 January.
- パラメータ:
year
- an int
year valuemonth
- an int
month valueday
- an int
day valuehour
- a double
hour valuegregflag
- an int
value
- 戻り値:
- a
double
value
swe_revjul
public static void swe_revjul(double jd,
int gregflag,
int[] jyear,
int[] jmon,
int[] jday,
double[] jut)
- Describe
swe_revjul
method here.
swe_revjul() is the inverse function to swe_julday(),
see the description there.
Arguments are julian day number, calendar flag (0=julian, 1=gregorian)
return values are the calendar day, month, year and the hour of
the day with decimal fraction (0 .. 23.999999).
Be aware the we use astronomical year numbering for the years
before Christ, not the historical year numbering.
Astronomical years are done with negative numbers, historical
years with indicators BC or BCE (before common era).
Year 0 (astronomical) = 1 BC historical year
year -1 (astronomical) = 2 BC historical year
year -234 (astronomical) = 235 BC historical year
etc.
Original author Mark Pottenger, Los Angeles.
with bug fix for year < -4711 16-aug-88 Alois Treindl
- パラメータ:
jd
- a double
valuegregflag
- an int
valuejyear
- an int
valuejmon
- an int
valuejday
- an int
valuejut
- a double
value