Ad-hoc basis. Usually comes out of studying the most common classes of computation and optimizing for it. For example, the "summing a series" probably falls ou

Ad-hoc basis. Usually comes out of studying the most common classes of computation and optimizing for it. For example, the "summing a series" probably falls out of loop optimizations: https://en.wikipedia.org/wiki/Loop_optimization https://en.wikipedia.org/wiki/Loop_optimization