Figure A1.

Let C = 1. We define a grid in the plane that runs parallel to the one spanned by the weighted unit vectors ${\tilde{\mathbf{e}}}_k$, with the barycenter of the former shifted to p. The grid consists of equally spaced convex combinations of the corner points $\left\{(\mathbf{p}-\mathbf{u})+{\tilde{\mathbf{e}}}_k\mid k=1,\dots ,N\right\}$.