!***************************************************
!  This program takes in the year month and day.  It
!  calculates the day of the year
!***************************************************
!program julian_date
subroutine julian_date(year,month,day,juldate)

integer :: year,month,day,juldate
integer :: leap_flag
integer, dimension(12) :: num_days
!year=2008
!month=4
!day=13

!******************************
!  Check if the year is a leap year
!******************************

leap_flag=0  !not a leap year
check4=mod(year,4)  !years divisible by 4 are leap years, unless...........
check100=mod(year,100)  !years also divisible by  100 are not leap years, except.......
check400=mod(year,400)  !years divisible by 400 are leap years.
if (  (check4 .eq. 0 .and. check100 .ne. 0) .or. (check400 .eq. 0) ) then
  leap_flag=1  !leap year
endif

!******************************
!  Make an array of the number of days
!******************************

if (leap_flag .eq. 0) then 
  ! J  F  M  A  M  J  J  A  S  O  N  D
  num_days=(/31,28,31,30,31,30,31,31,30,31,30,31/)
else if (leap_flag .eq. 1) then
  num_days=(/31,29,31,30,31,30,31,31,30,31,30,31/)
endif

!*****************************
!  Sum up the months of days
!*****************************

if (month .ge. 2) then
  do i=1,month-1
    juldate=juldate+num_days(i)
  enddo
else
  juldate=0
endif

!  Add on the extra days
juldate=juldate+day

!print*,year,month,day
!print*,juldate
!print*,'leap_flag',leap_flag

!end program
end subroutine julian_date