trunk/IOIPSL/calendar.f

MODULE calendar

  ! From IOIPSL/src/calendar.f90, version 2.0 2004/04/05 14:47:47

  ! This is the calendar used to do all calculations on time. Three
  ! types of calendars are possible:

  ! - Gregorian:
  ! The normal calendar. The time origin for the julian day in this
  ! case is 24 Nov -4713.

  ! - No leap:
  ! A 365 day year without leap years. The origin for the julian days
  ! is in this case 1 Jan 0.

  ! - xxxd:
  ! Year of xxx days with months of equal length. The origin for the
  ! julian days is then also 1 Jan 0.

  ! As one can see it is difficult to go from one calendar to the
  ! other. All operations involving julian days will be wrong. This
  ! calendar will lock as soon as possible the length of the year and
  ! forbid any further modification.

  ! For the non leap-year calendar the method is still brute force.
  ! We need to find an integer series which takes care of the length
  ! of the various month. (Jan)

  USE strlowercase_m, ONLY: strlowercase
  USE errioipsl, ONLY: histerr

  IMPLICIT NONE

  PRIVATE
  PUBLIC ymds2ju, ju2ymds, isittime, ioconf_calendar, itau2date, lock_unan, &
       calendar_used, un_an, un_jour

  REAL, PARAMETER:: un_jour = 86400. ! one day in seconds

  ! Description of calendar

  CHARACTER(LEN=20):: calendar_used = "gregorian"
  LOGICAL:: lock_unan = .FALSE.
  REAL:: un_an = 365.2425 ! one year in days
  INTEGER:: mon_len(12) = (/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)

  CHARACTER(LEN=3), PARAMETER:: cal(12) = (/'JAN', 'FEB', 'MAR', 'APR', &
       'MAY', 'JUN', 'JUL', 'AUG', 'SEP', 'OCT', 'NOV', 'DEC'/)

  REAL, SAVE:: start_day, start_sec

CONTAINS

  SUBROUTINE ymds2ju (year, month, day, sec, julian)

    INTEGER, INTENT(IN):: year, month, day
    REAL, INTENT(IN):: sec
    REAL, INTENT(OUT):: julian

    INTEGER:: julian_day
    REAL:: julian_sec

    !--------------------------------------------------------------------

    CALL ymds2ju_internal(year, month, day, sec, julian_day, julian_sec)
    julian = julian_day + julian_sec / un_jour

  END SUBROUTINE ymds2ju

  !===

  SUBROUTINE ymds2ju_internal (year, month, day, sec, julian_day, julian_sec)

    ! Converts year, month, day and seconds into a julian day

    ! In 1968 in a letter to the editor of Communications of the ACM
    ! (CACM, volume 11, number 10, October 1968, p.657) Henry F. Fliegel
    ! and Thomas C. Van Flandern presented such an algorithm.

    ! See also: http://www.magnet.ch/serendipity/hermetic/cal_stud/jdn.htm

    ! In the case of the Gregorian calendar we have chosen to use
    ! the Lilian day numbers. This is the day counter which starts
    ! on the 15th October 1582.
    ! This is the day at which Pope Gregory XIII introduced the
    ! Gregorian calendar.
    ! Compared to the true Julian calendar, which starts some
    ! 7980 years ago, the Lilian days are smaler and are dealt with
    ! easily on 32 bit machines. With the true Julian days you can only
    ! the fraction of the day in the real part to a precision of
    ! a 1/4 of a day with 32 bits.

    INTEGER, INTENT(IN):: year, month, day
    REAL, INTENT(IN):: sec

    INTEGER, INTENT(OUT):: julian_day
    REAL, INTENT(OUT):: julian_sec

    INTEGER:: jd, m, y, d, ml
    !--------------------------------------------------------------------
    lock_unan = .TRUE.

    m = month
    y = year
    d = day

    ! We deduce the calendar from the length of the year as it
    ! is faster than an INDEX on the calendar variable.

    ! Gregorian
    IF ( (un_an > 365.0).AND.(un_an < 366.0) ) THEN
       jd = (1461*(y+4800+INT(( m-14 )/12)))/4 &
            &      +(367*(m-2-12*(INT(( m-14 )/12))))/12 &
            &      -(3*((y+4900+INT((m-14)/12))/100))/4 &
            &      +d-32075
       jd = jd-2299160
       ! No leap or All leap
    ELSE IF (ABS(un_an-365.0) <= EPSILON(un_an) .OR. &
         &   ABS(un_an-366.0) <= EPSILON(un_an)) THEN
       ml = SUM(mon_len(1:m-1))
       jd = y*INT(un_an)+ml+(d-1)
       ! Calendar with regular month
    ELSE
       ml = INT(un_an)/12
       jd = y*INT(un_an)+(m-1)*ml+(d-1)
    ENDIF

    julian_day = jd
    julian_sec = sec

  END SUBROUTINE ymds2ju_internal

  !===

  SUBROUTINE ju2ymds (julian, year, month, day, sec)

    REAL, INTENT(IN):: julian

    INTEGER, INTENT(OUT):: year, month, day
    REAL, INTENT(OUT):: sec

    INTEGER:: julian_day
    REAL:: julian_sec
    !--------------------------------------------------------------------
    julian_day = INT(julian)
    julian_sec = (julian-julian_day)*un_jour

    CALL ju2ymds_internal(julian_day, julian_sec, year, month, day, sec)

  END SUBROUTINE ju2ymds

  !===

  SUBROUTINE ju2ymds_internal (julian_day, julian_sec, year, month, day, sec)

    ! This subroutine computes from the julian day the year,
    ! month, day and seconds

    ! In 1968 in a letter to the editor of Communications of the ACM
    ! (CACM, volume 11, number 10, October 1968, p.657) Henry F. Fliegel
    ! and Thomas C. Van Flandern presented such an algorithm.

    ! See also: http://www.magnet.ch/serendipity/hermetic/cal_stud/jdn.htm

    ! In the case of the Gregorian calendar we have chosen to use
    ! the Lilian day numbers. This is the day counter which starts
    ! on the 15th October 1582. This is the day at which Pope
    ! Gregory XIII introduced the Gregorian calendar.
    ! Compared to the true Julian calendar, which starts some 7980
    ! years ago, the Lilian days are smaler and are dealt with easily
    ! on 32 bit machines. With the true Julian days you can only the
    ! fraction of the day in the real part to a precision of a 1/4 of
    ! a day with 32 bits.

    INTEGER, INTENT(IN):: julian_day
    REAL, INTENT(IN):: julian_sec

    INTEGER, INTENT(OUT):: year, month, day
    REAL, INTENT(OUT):: sec

    INTEGER:: l, n, i, jd, j, d, m, y, ml
    INTEGER:: add_day
    !--------------------------------------------------------------------
    lock_unan = .TRUE.

    jd = julian_day
    sec = julian_sec
    IF (sec > un_jour) THEN
       add_day = INT(sec/un_jour)
       sec = sec-add_day*un_jour
       jd = jd+add_day
    ENDIF

    ! Gregorian
    IF ( (un_an > 365.0).AND.(un_an < 366.0) ) THEN
       jd = jd+2299160
   
       l = jd+68569
       n = (4*l)/146097
       l = l-(146097*n+3)/4
       i = (4000*(l+1))/1461001
       l = l-(1461*i)/4+31
       j = (80*l)/2447
       d = l-(2447*j)/80
       l = j/11
       m = j+2-(12*l)
       y = 100*(n-49)+i+l
       ! No leap or All leap
    ELSE IF (ABS(un_an-365.0) <= EPSILON(un_an) .OR. &
         &   ABS(un_an-366.0) <= EPSILON(un_an) ) THEN
       y = jd/INT(un_an)
       l = jd-y*INT(un_an)
       m = 1
       ml = 0
       DO WHILE (ml+mon_len(m) <= l)
          ml = ml+mon_len(m)
          m = m+1
       ENDDO
       d = l-ml+1
       ! others
    ELSE
       ml = INT(un_an)/12
       y = jd/INT(un_an)
       l = jd-y*INT(un_an)
       m = (l/ml)+1
       d = l-(m-1)*ml+1
    ENDIF

    day = d
    month = m
    year = y

  END SUBROUTINE ju2ymds_internal

  !===

  REAL FUNCTION itau2date (itau, date0, deltat)

    ! This function transforms itau into a date. The date whith which
    ! the time axis is going to be labeled

    ! INPUT
    !   itau: current time step
    !   date0: Date at which itau was equal to 0
    !   deltat: time step between itau s

    ! OUTPUT
    !   itau2date: Date for the given itau

    INTEGER:: itau
    REAL:: date0, deltat
    !--------------------------------------------------------------------
    itau2date = REAL(itau)*deltat/un_jour+date0

  END FUNCTION itau2date

  !===

  SUBROUTINE isittime &
       &  (itau, date0, dt, freq, last_action, last_check, do_action)

    ! This subroutine checks the time has come for a given action.
    ! This is computed from the current time-step(itau).
    ! Thus we need to have the time delta (dt), the frequency
    ! of the action (freq) and the last time it was done
    ! (last_action in units of itau).
    ! In order to extrapolate when will be the next check we need
    ! the time step of the last call (last_check).

    ! The test is done on the following condition:
    ! the distance from the current time to the time for the next
    ! action is smaller than the one from the next expected
    ! check to the next action.
    ! When the test is done on the time steps simplifactions make
    ! it more difficult to read in the code.
    ! For the real time case it is easier to understand !

    INTEGER, INTENT(IN):: itau
    REAL, INTENT(IN):: dt, freq
    INTEGER, INTENT(IN):: last_action, last_check
    REAL, INTENT(IN):: date0

    LOGICAL, INTENT(OUT):: do_action

    REAL:: dt_action, dt_check
    REAL:: date_last_act, date_next_check, date_next_act, &
         &        date_now, date_mp1, date_mpf
    INTEGER:: year, month, monthp1, day, next_check_itau, next_act_itau
    INTEGER:: yearp, dayp
    REAL:: sec, secp
    LOGICAL:: check = .FALSE.
    !--------------------------------------------------------------------
    IF (check) THEN
       WRITE(*, *) &
            &    "isittime 1.0 ", itau, date0, dt, freq, last_action, last_check
    ENDIF

    IF (last_check >= 0) THEN
       dt_action = (itau-last_action)*dt
       dt_check = (itau-last_check)*dt
       next_check_itau = itau+(itau-last_check)
   
       !- We are dealing with frequencies in seconds and thus operation
       !- can be done on the time steps.
   
       IF (freq > 0) THEN
          IF (ABS(dt_action-freq) <= ABS(dt_action+dt_check-freq)) THEN
             do_action = .TRUE.
          ELSE
             do_action = .FALSE.
          ENDIF
      
          !--- Here we deal with frequencies in month and work on julian days.
      
       ELSE
          date_now = itau2date (itau, date0, dt)
          date_last_act = itau2date (last_action, date0, dt)
          CALL ju2ymds (date_last_act, year, month, day, sec)
          monthp1 = month - freq
          yearp = year
      
          !--- Here we compute what logically should be the next month
      
          IF (month >= 13) THEN
             yearp = year+1
             monthp1 = monthp1-12
          ENDIF
          CALL ymds2ju (year, monthp1, day, sec, date_mpf)
      
          !--- But it could be that because of a shorter month or a bad
          !--- starting date that we end up further than we should be.
          !--- Thus we compute the first day of the next month.
          !--- We can not be beyond this date and if we are close
          !--- then we will take it as it is better.
      
          monthp1 = month+ABS(freq)
          yearp=year
          IF (monthp1 >= 13) THEN
             yearp = year+1
             monthp1 = monthp1 -12
          ENDIF
          dayp = 1
          secp = 0.0
          CALL ymds2ju (yearp, monthp1, dayp, secp, date_mp1)
      
          !--- If date_mp1 is smaller than date_mpf or only less than 4 days
          !--- larger then we take it. This needed to ensure that short month
          !--- like February do not mess up the thing !
      
          IF (date_mp1-date_mpf < 4.) THEN
             date_next_act = date_mp1
          ELSE
             date_next_act = date_mpf
          ENDIF
          date_next_check = itau2date (next_check_itau, date0, dt)
      
          !--- Transform the dates into time-steps for the needed precisions.
      
          next_act_itau = &
               &      last_action+INT((date_next_act-date_last_act)*(un_jour/dt))

          IF (   ABS(itau-next_act_itau) &
               &        <= ABS( next_check_itau-next_act_itau)) THEN
             do_action = .TRUE.
             IF (check) THEN
                WRITE(*, *) &
                     &         'ACT-TIME: itau, next_act_itau, next_check_itau: ', &
                     &         itau, next_act_itau, next_check_itau
                CALL ju2ymds (date_now, year, month, day, sec)
                WRITE(*, *) 'ACT-TIME: y, m, d, s: ', year, month, day, sec
                WRITE(*, *) &
                     &         'ACT-TIME: date_mp1, date_mpf: ', date_mp1, date_mpf
             ENDIF
          ELSE
             do_action = .FALSE.
          ENDIF
       ENDIF
   
       IF (check) THEN
          WRITE(*, *) "isittime 2.0 ", &
               &     date_next_check, date_next_act, ABS(dt_action-freq), &
               &     ABS(dt_action+dt_check-freq), dt_action, dt_check, &
               &     next_check_itau, do_action
       ENDIF
    ELSE
       do_action=.FALSE.
    ENDIF

  END SUBROUTINE isittime

  !===

  SUBROUTINE ioconf_calendar (str)

    ! This routine allows to configure the calendar to be used.
    ! This operation is only allowed once and the first call to
    ! ymds2ju or ju2ymsd will lock the current configuration.
    ! the argument to ioconf_calendar can be any of the following:
    !  - gregorian: This is the gregorian calendar (default here)
    !  - noleap: A calendar without leap years = 365 days
    !  - xxxd: A calendar of xxx days (has to be a modulo of 12)
    !                with 12 month of equal length

    CHARACTER(LEN=*), INTENT(IN):: str

    INTEGER:: leng, ipos
    CHARACTER(LEN=10):: str10
    !--------------------------------------------------------------------

    ! 1.0 Clean up the sring !

    CALL strlowercase (str)

    IF (.NOT.lock_unan) THEN

       lock_unan=.TRUE.

       SELECT CASE(str)
       CASE('gregorian')
          calendar_used = 'gregorian'
          un_an = 365.2425
          mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE('standard')
          calendar_used = 'gregorian'
          un_an = 365.2425
          mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE('proleptic_gregorian')
          calendar_used = 'gregorian'
          un_an = 365.2425
          mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE('noleap')
          calendar_used = 'noleap'
          un_an = 365.0
          mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE('365_day')
          calendar_used = 'noleap'
          un_an = 365.0
          mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE('365d')
          calendar_used = 'noleap'
          un_an = 365.0
          mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE('all_leap')
          calendar_used = 'all_leap'
          un_an = 366.0
          mon_len(:)=(/31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE('366_day')
          calendar_used = 'all_leap'
          un_an = 366.0
          mon_len(:)=(/31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE('366d')
          calendar_used = 'all_leap'
          un_an = 366.0
          mon_len(:)=(/31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
       CASE DEFAULT
          ipos = INDEX(str, 'd')
          IF (ipos == 4) THEN
             READ(str(1:3), '(I3)') leng
             IF ( (MOD(leng, 12) == 0).AND.(leng > 1) ) THEN
                calendar_used = str
                un_an = leng
                mon_len(:) = leng
             ELSE
                CALL histerr (3, 'ioconf_calendar', &
                     &         'The length of the year as to be a modulo of 12', &
                     &         'so that it can be divided into 12 month of equal length', &
                     &         str)
             ENDIF
          ELSE
             CALL histerr (3, 'ioconf_calendar', &
                  &       'Unrecognized input, please ceck the man pages.', str, ' ')
          ENDIF
       END SELECT
    ELSE
       WRITE(str10, '(f10.4)') un_an
       CALL histerr (2, 'ioconf_calendar', &
            &   'The calendar was already used or configured. You are not', &
            &   'allowed to change it again. '// &
            &   'The following length of year is used:', str10)
    ENDIF

  END SUBROUTINE ioconf_calendar

END MODULE calendar
1	MODULE calendar
2
3	! From IOIPSL/src/calendar.f90, version 2.0 2004/04/05 14:47:47
4
5	! This is the calendar used to do all calculations on time. Three
6	! types of calendars are possible:
7
8	! - Gregorian:
9	! The normal calendar. The time origin for the julian day in this
10	! case is 24 Nov -4713.
11
12	! - No leap:
13	! A 365 day year without leap years. The origin for the julian days
14	! is in this case 1 Jan 0.
15
16	! - xxxd:
17	! Year of xxx days with months of equal length. The origin for the
18	! julian days is then also 1 Jan 0.
19
20	! As one can see it is difficult to go from one calendar to the
21	! other. All operations involving julian days will be wrong. This
22	! calendar will lock as soon as possible the length of the year and
23	! forbid any further modification.
24
25	! For the non leap-year calendar the method is still brute force.
26	! We need to find an integer series which takes care of the length
27	! of the various month. (Jan)
28
29	USE strlowercase_m, ONLY: strlowercase
30	USE errioipsl, ONLY: histerr
31
32	IMPLICIT NONE
33
34	PRIVATE
35	PUBLIC ymds2ju, ju2ymds, isittime, ioconf_calendar, itau2date, lock_unan, &
36	calendar_used, un_an, un_jour
37
38	REAL, PARAMETER:: un_jour = 86400. ! one day in seconds
39
40	! Description of calendar
41
42	CHARACTER(LEN=20):: calendar_used = "gregorian"
43	LOGICAL:: lock_unan = .FALSE.
44	REAL:: un_an = 365.2425 ! one year in days
45	INTEGER:: mon_len(12) = (/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
46
47	CHARACTER(LEN=3), PARAMETER:: cal(12) = (/'JAN', 'FEB', 'MAR', 'APR', &
48	'MAY', 'JUN', 'JUL', 'AUG', 'SEP', 'OCT', 'NOV', 'DEC'/)
49
50	REAL, SAVE:: start_day, start_sec
51
52	CONTAINS
53
54	SUBROUTINE ymds2ju (year, month, day, sec, julian)
55
56	INTEGER, INTENT(IN):: year, month, day
57	REAL, INTENT(IN):: sec
58	REAL, INTENT(OUT):: julian
59
60	INTEGER:: julian_day
61	REAL:: julian_sec
62
63	!--------------------------------------------------------------------
64
65	CALL ymds2ju_internal(year, month, day, sec, julian_day, julian_sec)
66	julian = julian_day + julian_sec / un_jour
67
68	END SUBROUTINE ymds2ju
69
70	!===
71
72	SUBROUTINE ymds2ju_internal (year, month, day, sec, julian_day, julian_sec)
73
74	! Converts year, month, day and seconds into a julian day
75
76	! In 1968 in a letter to the editor of Communications of the ACM
77	! (CACM, volume 11, number 10, October 1968, p.657) Henry F. Fliegel
78	! and Thomas C. Van Flandern presented such an algorithm.
79
80	! See also: http://www.magnet.ch/serendipity/hermetic/cal_stud/jdn.htm
81
82	! In the case of the Gregorian calendar we have chosen to use
83	! the Lilian day numbers. This is the day counter which starts
84	! on the 15th October 1582.
85	! This is the day at which Pope Gregory XIII introduced the
86	! Gregorian calendar.
87	! Compared to the true Julian calendar, which starts some
88	! 7980 years ago, the Lilian days are smaler and are dealt with
89	! easily on 32 bit machines. With the true Julian days you can only
90	! the fraction of the day in the real part to a precision of
91	! a 1/4 of a day with 32 bits.
92
93	INTEGER, INTENT(IN):: year, month, day
94	REAL, INTENT(IN):: sec
95
96	INTEGER, INTENT(OUT):: julian_day
97	REAL, INTENT(OUT):: julian_sec
98
99	INTEGER:: jd, m, y, d, ml
100	!--------------------------------------------------------------------
101	lock_unan = .TRUE.
102
103	m = month
104	y = year
105	d = day
106
107	! We deduce the calendar from the length of the year as it
108	! is faster than an INDEX on the calendar variable.
109
110	! Gregorian
111	IF ( (un_an > 365.0).AND.(un_an < 366.0) ) THEN
112	jd = (1461*(y+4800+INT(( m-14 )/12)))/4 &
113	& +(367(m-2-12(INT(( m-14 )/12))))/12 &
114	& -(3*((y+4900+INT((m-14)/12))/100))/4 &
115	& +d-32075
116	jd = jd-2299160
117	! No leap or All leap
118	ELSE IF (ABS(un_an-365.0) <= EPSILON(un_an) .OR. &
119	& ABS(un_an-366.0) <= EPSILON(un_an)) THEN
120	ml = SUM(mon_len(1:m-1))
121	jd = y*INT(un_an)+ml+(d-1)
122	! Calendar with regular month
123	ELSE
124	ml = INT(un_an)/12
125	jd = yINT(un_an)+(m-1)ml+(d-1)
126	ENDIF
127
128	julian_day = jd
129	julian_sec = sec
130
131	END SUBROUTINE ymds2ju_internal
132
133	!===
134
135	SUBROUTINE ju2ymds (julian, year, month, day, sec)
136
137	REAL, INTENT(IN):: julian
138
139	INTEGER, INTENT(OUT):: year, month, day
140	REAL, INTENT(OUT):: sec
141
142	INTEGER:: julian_day
143	REAL:: julian_sec
144	!--------------------------------------------------------------------
145	julian_day = INT(julian)
146	julian_sec = (julian-julian_day)*un_jour
147
148	CALL ju2ymds_internal(julian_day, julian_sec, year, month, day, sec)
149
150	END SUBROUTINE ju2ymds
151
152	!===
153
154	SUBROUTINE ju2ymds_internal (julian_day, julian_sec, year, month, day, sec)
155
156	! This subroutine computes from the julian day the year,
157	! month, day and seconds
158
159	! In 1968 in a letter to the editor of Communications of the ACM
160	! (CACM, volume 11, number 10, October 1968, p.657) Henry F. Fliegel
161	! and Thomas C. Van Flandern presented such an algorithm.
162
163	! See also: http://www.magnet.ch/serendipity/hermetic/cal_stud/jdn.htm
164
165	! In the case of the Gregorian calendar we have chosen to use
166	! the Lilian day numbers. This is the day counter which starts
167	! on the 15th October 1582. This is the day at which Pope
168	! Gregory XIII introduced the Gregorian calendar.
169	! Compared to the true Julian calendar, which starts some 7980
170	! years ago, the Lilian days are smaler and are dealt with easily
171	! on 32 bit machines. With the true Julian days you can only the
172	! fraction of the day in the real part to a precision of a 1/4 of
173	! a day with 32 bits.
174
175	INTEGER, INTENT(IN):: julian_day
176	REAL, INTENT(IN):: julian_sec
177
178	INTEGER, INTENT(OUT):: year, month, day
179	REAL, INTENT(OUT):: sec
180
181	INTEGER:: l, n, i, jd, j, d, m, y, ml
182	INTEGER:: add_day
183	!--------------------------------------------------------------------
184	lock_unan = .TRUE.
185
186	jd = julian_day
187	sec = julian_sec
188	IF (sec > un_jour) THEN
189	add_day = INT(sec/un_jour)
190	sec = sec-add_day*un_jour
191	jd = jd+add_day
192	ENDIF
193
194	! Gregorian
195	IF ( (un_an > 365.0).AND.(un_an < 366.0) ) THEN
196	jd = jd+2299160
197
198	l = jd+68569
199	n = (4*l)/146097
200	l = l-(146097*n+3)/4
201	i = (4000*(l+1))/1461001
202	l = l-(1461*i)/4+31
203	j = (80*l)/2447
204	d = l-(2447*j)/80
205	l = j/11
206	m = j+2-(12*l)
207	y = 100*(n-49)+i+l
208	! No leap or All leap
209	ELSE IF (ABS(un_an-365.0) <= EPSILON(un_an) .OR. &
210	& ABS(un_an-366.0) <= EPSILON(un_an) ) THEN
211	y = jd/INT(un_an)
212	l = jd-y*INT(un_an)
213	m = 1
214	ml = 0
215	DO WHILE (ml+mon_len(m) <= l)
216	ml = ml+mon_len(m)
217	m = m+1
218	ENDDO
219	d = l-ml+1
220	! others
221	ELSE
222	ml = INT(un_an)/12
223	y = jd/INT(un_an)
224	l = jd-y*INT(un_an)
225	m = (l/ml)+1
226	d = l-(m-1)*ml+1
227	ENDIF
228
229	day = d
230	month = m
231	year = y
232
233	END SUBROUTINE ju2ymds_internal
234
235	!===
236
237	REAL FUNCTION itau2date (itau, date0, deltat)
238
239	! This function transforms itau into a date. The date whith which
240	! the time axis is going to be labeled
241
242	! INPUT
243	! itau: current time step
244	! date0: Date at which itau was equal to 0
245	! deltat: time step between itau s
246
247	! OUTPUT
248	! itau2date: Date for the given itau
249
250	INTEGER:: itau
251	REAL:: date0, deltat
252	!--------------------------------------------------------------------
253	itau2date = REAL(itau)*deltat/un_jour+date0
254
255	END FUNCTION itau2date
256
257	!===
258
259	SUBROUTINE isittime &
260	& (itau, date0, dt, freq, last_action, last_check, do_action)
261
262	! This subroutine checks the time has come for a given action.
263	! This is computed from the current time-step(itau).
264	! Thus we need to have the time delta (dt), the frequency
265	! of the action (freq) and the last time it was done
266	! (last_action in units of itau).
267	! In order to extrapolate when will be the next check we need
268	! the time step of the last call (last_check).
269
270	! The test is done on the following condition:
271	! the distance from the current time to the time for the next
272	! action is smaller than the one from the next expected
273	! check to the next action.
274	! When the test is done on the time steps simplifactions make
275	! it more difficult to read in the code.
276	! For the real time case it is easier to understand !
277
278	INTEGER, INTENT(IN):: itau
279	REAL, INTENT(IN):: dt, freq
280	INTEGER, INTENT(IN):: last_action, last_check
281	REAL, INTENT(IN):: date0
282
283	LOGICAL, INTENT(OUT):: do_action
284
285	REAL:: dt_action, dt_check
286	REAL:: date_last_act, date_next_check, date_next_act, &
287	& date_now, date_mp1, date_mpf
288	INTEGER:: year, month, monthp1, day, next_check_itau, next_act_itau
289	INTEGER:: yearp, dayp
290	REAL:: sec, secp
291	LOGICAL:: check = .FALSE.
292	!--------------------------------------------------------------------
293	IF (check) THEN
294	WRITE(, ) &
295	& "isittime 1.0 ", itau, date0, dt, freq, last_action, last_check
296	ENDIF
297
298	IF (last_check >= 0) THEN
299	dt_action = (itau-last_action)*dt
300	dt_check = (itau-last_check)*dt
301	next_check_itau = itau+(itau-last_check)
302
303	!- We are dealing with frequencies in seconds and thus operation
304	!- can be done on the time steps.
305
306	IF (freq > 0) THEN
307	IF (ABS(dt_action-freq) <= ABS(dt_action+dt_check-freq)) THEN
308	do_action = .TRUE.
309	ELSE
310	do_action = .FALSE.
311	ENDIF
312
313	!--- Here we deal with frequencies in month and work on julian days.
314
315	ELSE
316	date_now = itau2date (itau, date0, dt)
317	date_last_act = itau2date (last_action, date0, dt)
318	CALL ju2ymds (date_last_act, year, month, day, sec)
319	monthp1 = month - freq
320	yearp = year
321
322	!--- Here we compute what logically should be the next month
323
324	IF (month >= 13) THEN
325	yearp = year+1
326	monthp1 = monthp1-12
327	ENDIF
328	CALL ymds2ju (year, monthp1, day, sec, date_mpf)
329
330	!--- But it could be that because of a shorter month or a bad
331	!--- starting date that we end up further than we should be.
332	!--- Thus we compute the first day of the next month.
333	!--- We can not be beyond this date and if we are close
334	!--- then we will take it as it is better.
335
336	monthp1 = month+ABS(freq)
337	yearp=year
338	IF (monthp1 >= 13) THEN
339	yearp = year+1
340	monthp1 = monthp1 -12
341	ENDIF
342	dayp = 1
343	secp = 0.0
344	CALL ymds2ju (yearp, monthp1, dayp, secp, date_mp1)
345
346	!--- If date_mp1 is smaller than date_mpf or only less than 4 days
347	!--- larger then we take it. This needed to ensure that short month
348	!--- like February do not mess up the thing !
349
350	IF (date_mp1-date_mpf < 4.) THEN
351	date_next_act = date_mp1
352	ELSE
353	date_next_act = date_mpf
354	ENDIF
355	date_next_check = itau2date (next_check_itau, date0, dt)
356
357	!--- Transform the dates into time-steps for the needed precisions.
358
359	next_act_itau = &
360	& last_action+INT((date_next_act-date_last_act)*(un_jour/dt))
361
362	IF ( ABS(itau-next_act_itau) &
363	& <= ABS( next_check_itau-next_act_itau)) THEN
364	do_action = .TRUE.
365	IF (check) THEN
366	WRITE(, ) &
367	& 'ACT-TIME: itau, next_act_itau, next_check_itau: ', &
368	& itau, next_act_itau, next_check_itau
369	CALL ju2ymds (date_now, year, month, day, sec)
370	WRITE(, ) 'ACT-TIME: y, m, d, s: ', year, month, day, sec
371	WRITE(, ) &
372	& 'ACT-TIME: date_mp1, date_mpf: ', date_mp1, date_mpf
373	ENDIF
374	ELSE
375	do_action = .FALSE.
376	ENDIF
377	ENDIF
378
379	IF (check) THEN
380	WRITE(, ) "isittime 2.0 ", &
381	& date_next_check, date_next_act, ABS(dt_action-freq), &
382	& ABS(dt_action+dt_check-freq), dt_action, dt_check, &
383	& next_check_itau, do_action
384	ENDIF
385	ELSE
386	do_action=.FALSE.
387	ENDIF
388
389	END SUBROUTINE isittime
390
391	!===
392
393	SUBROUTINE ioconf_calendar (str)
394
395	! This routine allows to configure the calendar to be used.
396	! This operation is only allowed once and the first call to
397	! ymds2ju or ju2ymsd will lock the current configuration.
398	! the argument to ioconf_calendar can be any of the following:
399	! - gregorian: This is the gregorian calendar (default here)
400	! - noleap: A calendar without leap years = 365 days
401	! - xxxd: A calendar of xxx days (has to be a modulo of 12)
402	! with 12 month of equal length
403
404	CHARACTER(LEN=*), INTENT(IN):: str
405
406	INTEGER:: leng, ipos
407	CHARACTER(LEN=10):: str10
408	!--------------------------------------------------------------------
409
410	! 1.0 Clean up the sring !
411
412	CALL strlowercase (str)
413
414	IF (.NOT.lock_unan) THEN
415
416	lock_unan=.TRUE.
417
418	SELECT CASE(str)
419	CASE('gregorian')
420	calendar_used = 'gregorian'
421	un_an = 365.2425
422	mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
423	CASE('standard')
424	calendar_used = 'gregorian'
425	un_an = 365.2425
426	mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
427	CASE('proleptic_gregorian')
428	calendar_used = 'gregorian'
429	un_an = 365.2425
430	mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
431	CASE('noleap')
432	calendar_used = 'noleap'
433	un_an = 365.0
434	mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
435	CASE('365_day')
436	calendar_used = 'noleap'
437	un_an = 365.0
438	mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
439	CASE('365d')
440	calendar_used = 'noleap'
441	un_an = 365.0
442	mon_len(:)=(/31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
443	CASE('all_leap')
444	calendar_used = 'all_leap'
445	un_an = 366.0
446	mon_len(:)=(/31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
447	CASE('366_day')
448	calendar_used = 'all_leap'
449	un_an = 366.0
450	mon_len(:)=(/31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
451	CASE('366d')
452	calendar_used = 'all_leap'
453	un_an = 366.0
454	mon_len(:)=(/31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31/)
455	CASE DEFAULT
456	ipos = INDEX(str, 'd')
457	IF (ipos == 4) THEN
458	READ(str(1:3), '(I3)') leng
459	IF ( (MOD(leng, 12) == 0).AND.(leng > 1) ) THEN
460	calendar_used = str
461	un_an = leng
462	mon_len(:) = leng
463	ELSE
464	CALL histerr (3, 'ioconf_calendar', &
465	& 'The length of the year as to be a modulo of 12', &
466	& 'so that it can be divided into 12 month of equal length', &
467	& str)
468	ENDIF
469	ELSE
470	CALL histerr (3, 'ioconf_calendar', &
471	& 'Unrecognized input, please ceck the man pages.', str, ' ')
472	ENDIF
473	END SELECT
474	ELSE
475	WRITE(str10, '(f10.4)') un_an
476	CALL histerr (2, 'ioconf_calendar', &
477	& 'The calendar was already used or configured. You are not', &
478	& 'allowed to change it again. '// &
479	& 'The following length of year is used:', str10)
480	ENDIF
481
482	END SUBROUTINE ioconf_calendar
483
484	END MODULE calendar