Fig. 8.

Left: Contour plot of $c_{27}$ as a function of ${ϵ}_1$ and $\xi$ in a large region of parameter choices. Right: Zoom to the smaller region contained in the dark area of the left panel plot. The remaining parameters have the same values as in Fig. 6. Darker colors are smaller values and lighter colors are higher values of the cost function. The global minimum is located at $(0.513,0.256)$, but the cost function is rather close to the minimum in the large darker region in the right panel. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)