NCEPLIBS-w3emc/w3valdat_8f_source.html

      logical function w3valdat(idat)

      integer idat(8)

      real rinc1(5),rinc2(5)

      integer jdat(8)

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

!  essentially move the date and time by a zero time interval

!  and see if the same date and time is returned

      rinc1(1)=0

      rinc1(2:5)=idat(5:8)

      call w3reddat(-1,rinc1,rinc2)

      jldayn=iw3jdn(idat(1),idat(2),idat(3))+nint(rinc2(1))

      call w3fs26(jldayn,jdat(1),jdat(2),jdat(3),jdow,jdoy)

!  the time zone is valid if it is in signed hhmm format

!  with hh between -23 and 23 and mm equal to 00 or 30

      jdat(4)=mod(idat(4)/100,24)*100+mod(mod(idat(4),100),60)/30*30

      jdat(5:8)=nint(rinc2(2:5))

      w3valdat=all(idat.eq.jdat)

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


      end

iw3jdn
function iw3jdn(iyear, month, iday)
Computes julian day number from year (4 digits), month, and day.
Definition iw3jdn.f:42

w3fs26
subroutine w3fs26(jldayn, iyear, month, iday, idaywk, idayyr)
Computes year (4 digits), month, day, day of week, day of year from julian day number.
Definition w3fs26.f:56

w3reddat
subroutine w3reddat(it, rinc, dinc)
This subprogram reduces an ncep relative time interval into one of seven canonical forms,...
Definition w3reddat.f:86

w3valdat
logical function w3valdat(idat)
This logical function returns true if the input is a valid NCEP absolute date and time.
Definition w3valdat.f:18