\(\big\| \hat{x} \big\|\) =
\(\big\| x - \hat{x} \big\|\) =
\(\big\| d_{0 \rightarrow \hat{x}} \big\|\) =
\(\big\| d_{\hat{x} \rightarrow x} \big\|\) =
\(\mathcal{S}\) =
\(\big\| \hat{x} \big\|\) =
\(\big\| x - \hat{x} \big\|\) =
\(\big\| d_{0 \rightarrow \hat{x}} \big\|\) =
\(\big\| d_{\hat{x} \rightarrow x} \big\|\) =
\(\mathcal{S}\) =