A matrix with training targets 23, as a rank-2 tensor:
\[\begin{equation*} Y = \begin{pmatrix} \vphantom{\Big(} \vec{y}^1 & \cdots & \vec{y}^m \end{pmatrix} = \begin{pmatrix} y_1^1 & \cdots & y_1^m \\ \vdots & \ddots & \vdots \\ y_n^1 & \cdots & y_n^m \end{pmatrix} \in \mathbb{R}^{n \times m} \end{equation*} \]
where
and