da_diff_seconds.inc

1 real function da_diff_seconds (date_char_1, date_char_2)
2 
3    !-----------------------------------------------------------------------
4    ! Purpose: TBD
5    !-----------------------------------------------------------------------
6 
7    implicit none
8 
9    character(len=24), intent(in) :: date_char_1, date_char_2
10   
11    integer :: ccyy_1,mo_1,dd_1,hh_1,mi_1,ss_1,jd_1
12    integer :: ccyy_2,mo_2,dd_2,hh_2,mi_2,ss_2,jd_2
13    integer :: i, year, diff_days
14    integer :: start_year, end_year
15    integer :: mmday(12)
16  
17    real    :: s_1, s_2
18 
19    if (trace_use_dull) call da_trace_entry("da_diff_seconds")
20   
21    mmday=(/31,28,31,30,31,30,31,31,30,31,30,31/)
22   
23    read(date_char_1(1:19), fmt='(i4,1x,4(i2,1x),i2)') &
24         ccyy_1, &
25           mo_1, &
26           dd_1, &
27           hh_1, &
28           mi_1, &
29           ss_1
30   
31    read(date_char_2(1:19), fmt='(i4,1x,4(i2,1x),i2)') &
32         ccyy_2, &
33           mo_2, &
34           dd_2, &
35           hh_2, &
36           mi_2, &
37           ss_2
38 
39    if (ccyy_2 >= ccyy_1) then
40       start_year = ccyy_1
41       end_year   = ccyy_2
42    else
43       start_year = ccyy_2
44       end_year   = ccyy_1
45    end if
46 
47    diff_days = 0
48   
49    do year=start_year,end_year-1
50       diff_days = diff_days + 365
51       if (mod(year,4) == 0) then
52          diff_days = diff_days + 1
53 
54          if ((mod(year,100) == 0) .and. (mod(year,400) /= 0)) then
55             diff_days = diff_days - 1
56          end if
57       end if
58    end do
59 
60    if (mod(ccyy_1,4) == 0) then
61       mmday(2) = 29
62 
63       if((mod(ccyy_1,100) == 0) .and. (mod(ccyy_1,400) /= 0)) then
64          mmday(2) = 28
65       end if
66    end if
67 
68    jd_1 = dd_1
69 
70    do i=1,mo_1-1
71       jd_1=jd_1+mmday(i)
72    end do
73 
74    s_1 = real(ss_1) &
75        + 60.0*(real(mi_1) &
76        + 60.0*(real(hh_1) &
77        + 24.0* real(jd_1)))
78 
79    if (mod(ccyy_2,4) == 0) then
80       mmday(2) = 29
81 
82       if((mod(ccyy_2,100) == 0) .and. (mod(ccyy_2,400) /= 0)) then
83          mmday(2) = 28
84       end if
85    end if
86 
87    if (ccyy_2 >= ccyy_1) then
88       jd_2 = dd_2 + diff_days
89    else
90       jd_2 = dd_2 - diff_days
91    end if
92 
93    do i=1,mo_2-1
94       jd_2=jd_2+mmday(i)
95    end do
96 
97    s_2 = real(ss_2) &
98        + 60.0*(real(mi_2) &
99        + 60.0*(real(hh_2) &
100        + 24.0* real(jd_2)))
101 
102    da_diff_seconds = abs(s_1 - s_2)
103 
104    if (trace_use_dull) call da_trace_exit("da_diff_seconds")
105 
106 end function da_diff_seconds
107 
108