trunk/dyn3d/principal_cshift.f

module principal_cshift_m

  IMPLICIT NONE

contains

  subroutine principal_cshift(is2, xlon, xprimm)

    ! Add or subtract 2 pi so that xlon is near [-pi, pi], then cshift
    ! so that xlon is in ascending order. Make the same cshift on
    ! xprimm.

    ! Libraries:
    use nr_util, only: twopi

    use dynetat0_chosen_m, only: clon
    USE dimensions, ONLY: iim

    integer, intent(in):: is2
    real, intent(inout):: xlon(:), xprimm(:) ! (iim + 1)

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

    if (is2 /= 0) then
       IF (clon <= 0.) THEN
          IF (is2 /= 1) THEN
             xlon(:is2 - 1) = xlon(:is2 - 1) + twopi
             xlon(:iim) = cshift(xlon(:iim), shift = is2 - 1)
             xprimm(:iim) = cshift(xprimm(:iim), shift = is2 - 1)
          END IF
       else
          xlon(is2 + 1:iim) = xlon(is2 + 1:iim) - twopi
          xlon(:iim) = cshift(xlon(:iim), shift = is2)
          xprimm(:iim) = cshift(xprimm(:iim), shift = is2)
       end IF
    end if

    xlon(iim + 1) = xlon(1) + twopi
    xprimm(iim + 1) = xprimm(1)

  end subroutine principal_cshift

end module principal_cshift_m
1	module principal_cshift_m
2
3	IMPLICIT NONE
4
5	contains
6
7	subroutine principal_cshift(is2, xlon, xprimm)
8
9	! Add or subtract 2 pi so that xlon is near [-pi, pi], then cshift
10	! so that xlon is in ascending order. Make the same cshift on
11	! xprimm.
12
13	! Libraries:
14	use nr_util, only: twopi
15
16	use dynetat0_chosen_m, only: clon
17	USE dimensions, ONLY: iim
18
19	integer, intent(in):: is2
20	real, intent(inout):: xlon(:), xprimm(:) ! (iim + 1)
21
22	!-----------------------------------------------------
23
24	if (is2 /= 0) then
25	IF (clon <= 0.) THEN
26	IF (is2 /= 1) THEN
27	xlon(:is2 - 1) = xlon(:is2 - 1) + twopi
28	xlon(:iim) = cshift(xlon(:iim), shift = is2 - 1)
29	xprimm(:iim) = cshift(xprimm(:iim), shift = is2 - 1)
30	END IF
31	else
32	xlon(is2 + 1:iim) = xlon(is2 + 1:iim) - twopi
33	xlon(:iim) = cshift(xlon(:iim), shift = is2)
34	xprimm(:iim) = cshift(xprimm(:iim), shift = is2)
35	end IF
36	end if
37
38	xlon(iim + 1) = xlon(1) + twopi
39	xprimm(iim + 1) = xprimm(1)
40
41	end subroutine principal_cshift
42
43	end module principal_cshift_m