anchor.diff:  
       D => hecMAT%D
   
  -    !$OMP PARALLEL PRIVATE(I,K,X1,X2,X3,IXX)
  +    !$OMP PARALLEL PRIVATE(i)
       !$OMP DO
       do i= 1, hecMAT%N
         X1= X(4*i-3)
  
positive.code:       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
  
  
negative.code:     integer(kind=kint) :: I, K, NZ, IXX
      real(kind=kreal)   :: X1, X2, X3, X4
  
      !$OMP PARALLEL PRIVATE(I,K,X1,X2,X3,X4,IXX)
      !$OMP DO
      do I=1,N
        W1(I)=0.D0
  