Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: expectated value Date: Tue, 15 Jan 2013 18:47:14 +0000 (UTC) Organization: Istanbul Technical University Lines: 44 Message-ID: <kd487i$5pv$1@newscl01ah.mathworks.com> References: <kd31i0$ckc$1@newscl01ah.mathworks.com> <kd34i6$p21$1@speranza.aioe.org> <kd3p99$3qu$1@newscl01ah.mathworks.com> <kd3rgg$d1h$1@newscl01ah.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: www-00-blr.mathworks.com Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: newscl01ah.mathworks.com 1358275634 5951 172.30.248.45 (15 Jan 2013 18:47:14 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Tue, 15 Jan 2013 18:47:14 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 3940576 Xref: news.mathworks.com comp.soft-sys.matlab:786605 "Torsten" wrote in message <kd3rgg$d1h$1@newscl01ah.mathworks.com>... > "maryam" wrote in message <kd3p99$3qu$1@newscl01ah.mathworks.com>... > > "Nasser M. Abbasi" wrote in message <kd34i6$p21$1@speranza.aioe.org>... > > > On 01/15/2013 01:47 AM, maryam wrote: > > > > Dear friens > > > > I would like calculate the expectated value (E(.)) of a 1-by-1000 matrix > > > > {E(x)=sigma x*f(x)} > > > > how do I that? > > > > > > Apply the definition of expected value? > > > > > > when you are not sure how to do something, always look up > > > the definition and go from there. > > > > > > http://en.wikipedia.org/wiki/Expected_value > > > > > > If you have problem with implementing the defintion, then show > > > what you tried and where you are having problem. > > > > > > good luck, > > > > > > --Nasser > > -------------------- > > I know the the definition of expected value but I cant implement it. > > assume a 1-by-n arbitrary matrix, what's its matlab code? > > thanks > > A row of numbers does not have an expected value. > What you probably mean is an estimator for the expected value > of the random variable which produced the row of numbers. > Usually one takes > mean(A,2) > for this where A is your 1xn - matrix. > > Best wishes > Torsten. ----------------------------- Dear Torsten thanks your reply In the part of my thesis I obtain a vector of random variables that is I=1xn - matrix. then I must to calculate "contrast (I)" , the definition of contrast is contrast(x)=E(x^2)/(E(x))^2 and E(.) denoted the expectation operator. how could I calculate contrast (I)? thank you very much