I am reading a paper where I encountered the following -
\begin{equation} Z(x) = \pi_{[-c,c]^{n}} (\nabla F(x)-x) \end{equation}
what does the first term mean? Its mentioned in the paper that $\pi_{[-c,c]^{n}} (q)$ is projection and it acts components wise on q - Which I cannot understand. Can someone elaborate on it?