[jandrewrogers]

Any algorithm directly expressible as an electronic circuit is considered patentable in most countries due to this equivalence relationship. Technically, this includes all computing algorithms in practice, since there is no meaningful distinction between software and hardware.

However, this is also why business method algorithms like the Amazon "One-Click" are not patentable in most countries. There is no trivial theoretical equivalence between one-click shopping and an electronic circuit.