`Bump´ circuits for computing similarity and dissimilarity of analog voltages

The author describes two small analog circuits that compute generalised measures of the similarity of two voltage inputs. The similarity outputs from the circuits, given as currents, become large when the input voltages are close to each other. One of the circuits, the bump circuit, computes only this similarity output. The other circuit, the bump-anti-bump circuit, computes the similarity output as well as the dissimilarity measure. Each of its dissimilarity outputs becomes large only when the corresponding input is sufficiently larger than the other input. The dissimilarity outputs can be summed together or left separate; when left separate, they resemble generalised rectifier outputs. Test results are presented that illustrate these transfer characteristics