  A map is a panorama in small scale. In this half-survey, half-research paper
we give general results on Ramanujan expansions. We don't include the ocean of
results from the literature on the two classes (see Schwarz-Spilker Book, also
Lucht's survey for these) of additive and multiplicative functions while we
include, say, the two new (not simply connected) lands of finite Ramanujan
expansions (see my paper, with Murty & Saha) and of shift-Ramanujan expansions
(see my subsequent paper, with Murty) .
