  For G = SL(3,R) and G = SO(2,n), we give explicit, practical conditions that
determine whether or not a closed, connected subgroup H of G has the property
that there exists a compact subset C of G with CHC = G. To do this, we fix a
Cartan decomposition G = KAK of G, and then carry out an approximate
calculation of the intersection of KHK with A, for each closed, connected
subgroup H of G.
