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Q: Statistical Average ( No Answer,   0 Comments )
Question  
Subject: Statistical Average
Category: Science > Math
Asked by: chishmishdeez-ga
List Price: $5.00
Posted: 19 Sep 2006 07:25 PDT
Expires: 19 Oct 2006 07:25 PDT
Question ID: 766571
how do u implement statistical average for a sinusoid
e.g
i want to implement process

y=(1/sqrt(N))*sum(cos(wd*cos(alphan')*t+phin'*ones(1,Ns)));

where alphan is 1 by N random mumber 
Ns=5000;
t=[0:Ns-1]*Ts
Ts= sampling period.
phin is again random number 1 by N

after summation i get y as 1 by Ns RV which is as expected. Bu tthis
is just a one sample. its mean is 0 and variance turns out to be
nearly 0.5

but due to  random nature, we should have ensemble avg 

loop=10
for i=1:loop
y(i,:)=(1/sqrt(N))*sum(cos(wd*cos(alphan')*t+phin'*ones(1,Ns)));
end

ymean=mean(y)

i believe this is how ensemble calculated

but why does variance change... should it change and if yes how to get
variance 0.5 as a single sample...

help
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