anchor.diff:  
      DO nelem=1,elem_total
          Nuu0(:) = uuN0(:,nelem)
  -       CALL BD_ElemNodalDisp(uuN,node_elem,dof_node,nelem,Nuuu)
  +       CALL BD_ElemNodalDisp(uuN,node_elem,dof_node,nelem,Nuuu,ErrStat2,ErrMsg2)
          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)
  +       CALL BD_ElemNodalDisp(vvN,node_elem,dof_node,nelem,Nvvv,ErrStat2,ErrMsg2)
  +       CALL BD_ElemNodalDisp(aaN,node_elem,dof_node,nelem,Naaa,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)
  
positive.code:    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(:,:)
  
     REAL(ReKi),          ALLOCATABLE:: Nuu0(:)
     REAL(ReKi),          ALLOCATABLE:: Nuuu(:)
  
negative.code:        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,ErrStat2,ErrMsg2)
  
         CALL BD_StaticElementMatrixForce(Nuu0,Nuuu,Nrr0,Nrrr,Nvvv,EStif0_GL,EMass0_GL,gravity,DistrLoad_GL,&
                                          ngp,node_elem,dof_node,elf)
  