Returns the intersection of the two bases, i.e. the size of a sector in the returned basis is the minimum of the sizes in the two input bases.
References syten::Basis::dir, syten::Basis::elementSize(), SYTEN_ASSERT_DEBUG, and SYTEN_ASSERT_MSG.
Referenced by syten::T3N::RandomState::generateNearVacuumState(), syten::T3N::RandomState::generateNearVacuumState_rec(), syten::IPEPS::grow_bottom_rung(), syten::IPEPS::grow_left_rung(), syten::IPEPS::grow_right_rung(), syten::IPEPS::grow_top_rung(), and syten::IPEPS::sldlmap().