anchor.diff:      integer(kind=kint) :: I, K, NZ, IXX
       real(kind=kreal)   :: X1, X2, X3, X4
   
  +    !$OMP PARALLEL PRIVATE(I,K,X1,X2,X3,IXX)
  +    !$OMP DO
       do I=1,N
         W1(I)=0.D0
         W2(I)=0.D0
         W3(I)=0.D0
         W4(I)=0.D0
       enddo
  +    !$OMP END DO
   
       do NZ=1,MJAD
  +      !$OMP DO
         do K=IAJAD(NZ),IAJAD(NZ+1)-1
           X1=X(JAJAD(K)*4-3)
           X2=X(JAJAD(K)*4-2)
  
positive.code: 
      D => hecMAT%D
  
      do i= 1, hecMAT%N
        X1= X(4*i-3)
        X2= X(4*i-2)
  
negative.code:       Y(4*i-1)= D(16*i- 7)*X1 + D(16*i- 6)*X2 + D(16*i- 5)*X3 + D(16*i- 4)*X4
        Y(4*i  )= D(16*i- 3)*X1 + D(16*i- 2)*X2 + D(16*i- 1)*X3 + D(16*i- 0)*X4
      enddo
      !$OMP END DO
      call MATJAD(hecMAT%N, MJAD, IAJAD, JAJAD, AJAD, JADORD, X, Y, WP1, WP2, WP3, WP4)
    end subroutine hecmw_JAD_MATVEC_44
  
  