| 1 |
module ymds2ju_m |
| 2 |
|
| 3 |
implicit none |
| 4 |
|
| 5 |
contains |
| 6 |
|
| 7 |
SUBROUTINE ymds2ju (year, month, day, sec, julian) |
| 8 |
|
| 9 |
! Converts year, month, day and seconds into a julian day |
| 10 |
|
| 11 |
! In 1968 in a letter to the editor of Communications of the ACM |
| 12 |
! (CACM, volume 11, number 10, October 1968, p.657) Henry F. Fliegel |
| 13 |
! and Thomas C. Van Flandern presented such an algorithm. |
| 14 |
|
| 15 |
! See also: http://www.magnet.ch/serendipity/hermetic/cal_stud/jdn.htm |
| 16 |
|
| 17 |
! In the case of the Gregorian calendar we have chosen to use |
| 18 |
! the Lilian day numbers. This is the day counter which starts |
| 19 |
! on the 15th October 1582. |
| 20 |
! This is the day at which Pope Gregory XIII introduced the |
| 21 |
! Gregorian calendar. |
| 22 |
! Compared to the true Julian calendar, which starts some |
| 23 |
! 7980 years ago, the Lilian days are smaler and are dealt with |
| 24 |
! easily on 32 bit machines. With the true Julian days you can only |
| 25 |
! the fraction of the day in the real part to a precision of |
| 26 |
! a 1/4 of a day with 32 bits. |
| 27 |
|
| 28 |
USE calendar, ONLY: lock_unan, un_jour |
| 29 |
USE ioconf_calendar_m, ONLY: mon_len, un_an |
| 30 |
|
| 31 |
INTEGER, INTENT(IN):: year, month, day |
| 32 |
REAL, INTENT(IN):: sec |
| 33 |
REAL, INTENT(OUT):: julian |
| 34 |
|
| 35 |
! Local: |
| 36 |
|
| 37 |
INTEGER:: julian_day |
| 38 |
REAL:: julian_sec |
| 39 |
INTEGER:: jd, m, y, d, ml |
| 40 |
|
| 41 |
!-------------------------------------------------------------------- |
| 42 |
|
| 43 |
lock_unan = .TRUE. |
| 44 |
|
| 45 |
m = month |
| 46 |
y = year |
| 47 |
d = day |
| 48 |
|
| 49 |
! We deduce the calendar from the length of the year as it |
| 50 |
! is faster than an INDEX on the calendar variable. |
| 51 |
|
| 52 |
! Gregorian |
| 53 |
IF ( (un_an > 365.0).AND.(un_an < 366.0) ) THEN |
| 54 |
jd = (1461*(y+4800+INT(( m-14 )/12)))/4 & |
| 55 |
& +(367*(m-2-12*(INT(( m-14 )/12))))/12 & |
| 56 |
& -(3*((y+4900+INT((m-14)/12))/100))/4 & |
| 57 |
& +d-32075 |
| 58 |
jd = jd-2299160 |
| 59 |
! No leap or All leap |
| 60 |
ELSE IF (ABS(un_an-365.0) <= EPSILON(un_an) .OR. & |
| 61 |
& ABS(un_an-366.0) <= EPSILON(un_an)) THEN |
| 62 |
ml = SUM(mon_len(1:m-1)) |
| 63 |
jd = y*INT(un_an)+ml+(d-1) |
| 64 |
! Calendar with regular month |
| 65 |
ELSE |
| 66 |
ml = INT(un_an)/12 |
| 67 |
jd = y*INT(un_an)+(m-1)*ml+(d-1) |
| 68 |
ENDIF |
| 69 |
|
| 70 |
julian_day = jd |
| 71 |
julian_sec = sec |
| 72 |
|
| 73 |
julian = julian_day + julian_sec / un_jour |
| 74 |
|
| 75 |
END SUBROUTINE ymds2ju |
| 76 |
|
| 77 |
end module ymds2ju_m |
Parent Directory
| 
Revision Log