[Boost-users] [uBLAS] howto combine sparse AND symmetric?

Hi! I need to solve the classical linear equation A*x=b with x the unknown vector and A a very large, sparse and symmetrical matrix. I want to try the conjugate gradient iterative method to solve the problem (unless somebody knows a definitely much better one). Now I've seen that uBLAS provides the symmetric_adaptor class - should I use this one in combination with one of the sparse matrix classes? Does this reduce the memory usage as compared to only using a sparse matrix? Many thanks in advance Tim Odenthal