On Ramanujan smooth expansions for a general arithmetic function

We study in detail the Ramanujan smooth expansions, for arithmetic functions; we start with the most general ones, for which we supply the “$P-$local expansions”, for arguments with all prime-factors $p\le P$ (namely, $P-$smooth arguments), that are also square-free; then, we supply general results for interesting subsets of arithmetic functions, regarding both their $P-$local and (global) Ramanujan smooth expansions.