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maryam
Posts:
17
Registered:
12/25/12


Re: expectated value
Posted:
Jan 15, 2013 1:47 PM


"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 1by1000 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 1byn 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



