page 222, equation 6.22, 3rd edition

[ryanyu512]

Yz = [1_mm, 0_mx;
Gx, 0_2*(M-3), Gz)

If M = 0, then M - 3 is negative. It seems confusing

[petercorke]

Thanks for picking this up. This is insertion Jacobian for the SLAM case, for the landmark-only case there should be no ${\bf G}_x$ and the zeros after it should be ${\bf 0}_{2 \times M}$