anchor.diff:     INTEGER(IntKi),    INTENT(IN   ):: node_elem
      INTEGER(IntKi),    INTENT(IN   ):: dof_node
      INTEGER(IntKi),    INTENT(IN   ):: ngp
  -
      REAL(ReKi),        INTENT(  OUT):: StifK(:,:)
      REAL(ReKi),        INTENT(  OUT):: RHS(:)
      REAL(ReKi),        INTENT(  OUT):: MassM(:,:)
      REAL(ReKi),        INTENT(  OUT):: DampG(:,:)
  +   INTEGER(IntKi),    INTENT(  OUT):: ErrStat       ! Error status of the operation
  +   CHARACTER(*),      INTENT(  OUT):: ErrMsg        ! Error message if ErrStat /= ErrID_None
   
      REAL(ReKi),          ALLOCATABLE:: Nuu0(:)
      REAL(ReKi),          ALLOCATABLE:: Nuuu(:)
  
positive.code: 
     DO nelem=1,elem_total
         Nuu0(:) = uuN0(:,nelem)
         CALL BD_ElemNodalDisp(uuN,node_elem,dof_node,nelem,Nuuu)
         CALL BD_NodalRelRot(Nuu0,node_elem,dof_node,Nrr0)
         CALL BD_NodalRelRot(Nuuu,node_elem,dof_node,Nrrr)
         CALL BD_ElemNodalDisp(vvN,node_elem,dof_node,nelem,Nvvv)
         CALL BD_ElemNodalDisp(aaN,node_elem,dof_node,nelem,Naaa)
         temp_id = (nelem-1)*ngp
         DO j=1,ngp
             EStif0_GL(1:6,1:6,j) = Stif0(1:6,1:6,temp_id+j)
  
negative.code: 
     DO nelem=1,elem_total
         Nuu0(:) = uuN0(:,nelem)
         CALL BD_ElemNodalDisp(uuN,node_elem,dof_node,nelem,Nuuu,ErrStat2,ErrMsg2)
         temp_id = (nelem-1)*ngp
         DO j=1,ngp
             EStif0_GL(1:6,1:6,j) = Stif0(1:6,1:6,temp_id+j)
  