#include "dims.h"
      SUBROUTINE DLDP(NX,XL,XP,LEN)
      use cons_module,only: dlamda_2div3, dlamda_1div12,
     |                      dphi_2div3,   dphi_1div12
      implicit none
#include "params.h"
#include "fcom.h"
#include "buff.h"
!
! Args:
      integer,intent(in) :: nx,len
      real,intent(out) :: XL(ZIMXP,ZKMXP),XP(ZIMXP,ZKMXP)
!
! Local:
      integer :: lenp2,i,nxk,nxjp2k,nxjp1k,nxjm1k,nxjm2k
!
! cons_module:
!    |  dlamda_2div3,   ! 2./(3.*dlamda)        C(10)
!    |  dlamda_1div12,  ! 1./(12.*dlamda)       C(11)
!    |  dphi_2div3,     ! 2./(3.*dphi)          C(12)
!    |  dphi_1div12,    ! 1./(12.*dphi)         C(13)
!
      LENP2=LEN+2
C     ****                   COMPUTE LONGITUDINAL DERIVATIVE
      NXK   = NJ+NX
      DO 10 I=3,LENP2
      XL(I,1)=dlamda_2div3 *(F(I+1,NXK)-F(I-1,NXK))-
     |        dlamda_1div12*(F(I+2,NXK)-F(I-2,NXK))
   10 CONTINUE
C     ****                   COMPUTE LATITUDINAL DERIVATIVE
      NXJP2K= NJP2+NX
      NXJP1K= NJP1+NX
      NXJM1K= NJM1+NX
      NXJM2K= NJM2+NX
      DO 20 I=3,LENP2
      XP(I,1)=dphi_2div3 *(F(I,NXJP1K)-F(I,NXJM1K))-
     1        dphi_1div12*(F(I,NXJP2K)-F(I,NXJM2K))
   20 CONTINUE
      RETURN
      END
C