If $A\in B(H)$ is a linear operator acting on a complex Hilbert space $H$ then, by Theorem~\ref{glavni}, $A\perp_R I$ if and only if $DV_{ub}(A)=DV_{ub}(-A)$, where
$$
DV_{ub}(A)=\{(\mu,r)\in\overline{DW(A)}:\, r=\max \mathcal{L}_\mu(A)\},
$$
$$
\mathcal{L}_\mu(A)=\{\lim_{n\rightarrow\infty}(A^*Ax_n,x_n):\, x_n\in H, \|x_n\|=1, \lim_{n\rightarrow\infty}(Ax_n,x_n)=\mu\},
$$
if $H$ is infinite-dimensional, while for $3\le \textup{dim\,}H<\infty$ we have a simpler representation
$$
DV_{ub}(A)=\{(\mu,r)\in DW(A):\, r=\max\mathcal{L}_\mu(A)\},
$$
$$
\mathcal{L}_{\mu}(A)=\{(A^*Ax,x):\, x\in H, \|x\|=1, (Ax,x)=\mu\}.
$$