Computational complexity seems like a useful frame for thinking about such distinctions. If you can calculate the state of a system at time t in O(log t), that'

Computational complexity seems like a useful frame for thinking about such distinctions. If you can calculate the state of a system at time t in O(log t), that's a lot like having a closed-form solution. On the other hand if the calculation takes O(t) time, then it seems much less like a closed-form solution and more like a step-by-step simulation.