Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: Center of gravity of discrete graph Date: Mon, 9 Feb 2009 20:31:02 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 7 Message-ID: <gmq3q6$3oo$1@fred.mathworks.com> References: <gmq041$2g2$1@fred.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: webapp-03-blr.mathworks.com Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1234211462 3864 172.30.248.38 (9 Feb 2009 20:31:02 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Mon, 9 Feb 2009 20:31:02 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1187260 Xref: news.mathworks.com comp.soft-sys.matlab:517163 "rocky99 Therminator" <ronenk@mail.com> wrote in message <gmq041$2g2$1@fred.mathworks.com>... > I'd like to find the center of gravity of a discrete graph. I have the vector (1x200) of the values of the x-axis and the vector (1x200) of the values of the y-axis. (Y is a spectrum and X is a frequency). I need the frequency (x-value) of the center of gravity of this graph. > Any help would be highly appreciated. Thanks What do you mean here by the "center of gravity"? If each point is considered to have a weight of one, then the graph's center of gravity would have an x-value of mean(x), which is totally independent of the y-values. Perhaps you mean to have the "center of gravity" of the x-values weighted by the corresponding y-values. Then it would be mean(x.*y)/mean(y). It all depends on what meaning you have in mind for a "center of gravity." Roger Stafford