subroutine mvprod_psas(NDIM,a,XX,AX,izs,rzs,dzs),4
      implicit none
      include 'champ.cdk'
      include 'chobs.cdk'

      integer  NDIM, i, izs(1)
      integer NOBS,IR
      real*8 AX(NDIM), XX(NDIM)
      real dl_v(2*N*N)
C      real*8 dl_v(2*N*N)
      real*8   rzs(1), dzs(1),a(1)
      real*8 XJ
      EXTERNAL PSASVAR 

      DO IR =1 ,NDIM
       dl_v(IR) = XX(IR)
      END DO

       XJ=0.0
       DO IR = 1,NDIM
         dl_v(IR) = dl_v(IR)/sigmao(IR)
       END DO 

       CALL HT(dl_v,ZF,SO)
       CALL SQRTBT(ZF,ZR)
       CALL SQRTB(ZR,ZF)
       CALL H(ZF,SO,dl_v)

       DO IR = 1,NDIM
         dl_v(IR) = dl_v(IR)/sigmao(IR)
         AX(IR) =  DBLE(dl_v(IR)) +  XX(IR)
       END DO

c       call psasvar(NDIM,XX,XJ)
      end subroutine