Say i have a summation,
$\sum_{i=1}^{n}(\alpha^{+(i)} - \alpha^{-(i)})$
If i were to change it into vector format it would be,
\begin{bmatrix} \alpha^+\\ \alpha^- \end{bmatrix}
In the reference book it is written as,
\begin{bmatrix} \alpha^+\\ -\alpha^- \end{bmatrix}
This is obtained from "Engineering Design via Surrogate Modelling: A Practical Guide, Forrester" describing the steps for SVR. I am having trouble as to how in Forrester they could change the summation into the vector format as shown above.