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module ymds2ju_internal_m |
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|
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implicit none |
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|
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contains |
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|
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SUBROUTINE ymds2ju_internal (year, month, day, sec, julian_day, julian_sec) |
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|
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! Converts year, month, day and seconds into a julian day |
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|
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! In 1968 in a letter to the editor of Communications of the ACM |
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! (CACM, volume 11, number 10, October 1968, p.657) Henry F. Fliegel |
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! and Thomas C. Van Flandern presented such an algorithm. |
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|
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! See also: http://www.magnet.ch/serendipity/hermetic/cal_stud/jdn.htm |
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|
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! In the case of the Gregorian calendar we have chosen to use |
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! the Lilian day numbers. This is the day counter which starts |
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! on the 15th October 1582. |
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! This is the day at which Pope Gregory XIII introduced the |
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! Gregorian calendar. |
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! Compared to the true Julian calendar, which starts some |
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! 7980 years ago, the Lilian days are smaler and are dealt with |
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! easily on 32 bit machines. With the true Julian days you can only |
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! the fraction of the day in the real part to a precision of |
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! a 1/4 of a day with 32 bits. |
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|
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use calendar |
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|
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INTEGER, INTENT(IN):: year, month, day |
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REAL, INTENT(IN):: sec |
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|
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INTEGER, INTENT(OUT):: julian_day |
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REAL, INTENT(OUT):: julian_sec |
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INTEGER:: jd, m, y, d, ml |
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!-------------------------------------------------------------------- |
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lock_unan = .TRUE. |
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|
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m = month |
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y = year |
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d = day |
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|
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! We deduce the calendar from the length of the year as it |
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! is faster than an INDEX on the calendar variable. |
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|
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! Gregorian |
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IF ( (un_an > 365.0).AND.(un_an < 366.0) ) THEN |
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jd = (1461*(y+4800+INT(( m-14 )/12)))/4 & |
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& +(367*(m-2-12*(INT(( m-14 )/12))))/12 & |
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& -(3*((y+4900+INT((m-14)/12))/100))/4 & |
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& +d-32075 |
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jd = jd-2299160 |
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! No leap or All leap |
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ELSE IF (ABS(un_an-365.0) <= EPSILON(un_an) .OR. & |
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& ABS(un_an-366.0) <= EPSILON(un_an)) THEN |
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ml = SUM(mon_len(1:m-1)) |
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jd = y*INT(un_an)+ml+(d-1) |
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! Calendar with regular month |
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ELSE |
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ml = INT(un_an)/12 |
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jd = y*INT(un_an)+(m-1)*ml+(d-1) |
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ENDIF |
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|
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julian_day = jd |
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julian_sec = sec |
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|
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END SUBROUTINE ymds2ju_internal |
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|
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end module ymds2ju_internal_m |
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