text: As the shock wave evolves in time, its strength decreases. The self-similar solution described above breaks down when  becomes comparable to  (more precisely, when ). At this later stage of the evolution,  (and consequently ) cannot be neglected. This means that the evolution is not self-similar, because one can form a length scale  and a time scale  to describe the problem. The governing equations are then integrated numerically, as was done by H. Goldstine and John von Neumann, Brode, and Okhotsimskii et al.