Talk:Dirichlet convolution

Latest comment: 5 years ago by Wqwt in topic Dirichlet hyperbola method

[Untitled] edit

Explain why its a Dirichlet ring, and not a field_(mathematics). Naively, it seems to have additive and multiplicative units and inverses. linas 05:00, 6 Jan 2005 (UTC)

Because only arithmetic functions for which f(1) is not 0 have inverses. I have clarified this in the article. Gandalf61 10:25, May 21, 2005 (UTC)

Weak multiplicative functions edit

Where do these come from? Are they the same as multiplicative (in the number-theoretic sense)? Richard Pinch (talk) 21:45, 3 September 2008 (UTC)Reply

Yeah it looks like it just means multiplicative. The results proved in that section is that (f*g)(mn)=(f*g)(m)·(f*g)(n) for relatively prime integers m,n, which is just the definition of multiplicative. A google search for "weak multiplicative functions" returned essentially 2 results (one of which was this wiki article), so I'm removing the term weak. RobHar (talk) 23:56, 3 September 2008 (UTC)Reply
Actually, I decided to just remove the whole section, as it was poorly written, it reiterates a statement made in the previous section, and the proof is already in the article Multiplicative functions. RobHar (talk) 00:00, 4 September 2008 (UTC)Reply
Thanks for sorting that out. Richard Pinch (talk) 07:00, 4 September 2008 (UTC)Reply

Special case of general convolution concept edit

The article says, correctly, that the Dirichlet convolution is analogous to the ordinary convolution of functions on the reals. But it seems to me that one can say more than that, namely, both are special cases of the same concept, convolution on a monoid. (Going a bit farther than the usual case of groups, which is discussed at convolution.) Is that worth putting in the article? Is there a good reference for it? -- Spireguy (talk) 16:28, 23 July 2010 (UTC)Reply

What does this mean? edit

The article states "Given a completely multiplicative function f then f (g*h) = (f g)*(f h). "

Is (f g) pointwise multipllication?


Virginia-American (talk) 19:22, 22 December 2011 (UTC)Reply

Yes it is. It's defined in the article on completely multiplicative functions.

Virginia-American (talk) 15:45, 23 December 2011 (UTC)Reply

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Dirichlet hyperbola method edit

Would be nice to have section or article on this http://planetmath.org/dirichlethyperbolamethod Wqwt (talk) 20:47, 28 May 2018 (UTC)Reply