The HLL and HLLC solvers

An approximation scheme for the Godunov method would either be one that a) approximates the values of p and u in the star region, from which the numerical flux can be directly computed, or b) approximates the numerical flux itself. The approximate Riemann solvers we learned about before, on wiki page on PVRS, TRRS, TSRS, and the like are approximation methods of type 'a'. The HLL and HLLC solvers are approximation techniques of type 'b'.