nostr:npub1srhg4hk63ew68kepu0znazgf9tdl089dkur5artp440htxqrc8zsqz8g90 i should rephrase - one set of indices away from one another. So forward, backward, up and down if you're thinking 2 dimensionally
nostr:npub1kdyzl44h6mhyl4djtf20w0t7avsy09umshq2k2czjf62ps774phqcd2hnf depends on your definition of local, because only two points can be an index away from any particular one.
Discussion
nostr:npub1kdyzl44h6mhyl4djtf20w0t7avsy09umshq2k2czjf62ps774phqcd2hnf are you trying to map a cartesian grid to polar coordinates?