Figure 6

Projection of the code maps onto the plane of the first two principal components (see text for details). Red 'x' signs, random codes, r; red circles, codes resulting from optimization of random codes, o; green squares, random codes that perform better than the standard code, R; green asterisks, codes resulting from optimization of the set R, O; blue square, the standard code; blue asterisk, the code resulting from the optimization of the standard code. (a) PRS; (b) the Gilis matrix.