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New to MATLAB?

find the mean, energy and power of cosine function

Asked by Passband Modulation on 21 Sep 2012
Latest activity Commented on by Walter Roberson

Walter Roberson (view profile)

on 18 Dec 2013

i am just a matlab beginner.

x[n]=2cos(0.2*pi*n) with a length of N =100 , that is, ,0<N<99 plotted

 clear all
 n=[0:99];
 x=2*cos(0.2*pi*n);
 stem(n,x);
 legend('x[n]');
 title('Sequence of 2*cos(0.2*pi*n)');
 xlabel('n');
 ylabel('x[n]');
 axis([0 99 -2 2]);

how to use MATLAB to compute the mean, and energy and power of x[n]given mean=x, energy=Ex and power=Px.

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1 Answer

Answer by Wayne King

Wayne King (view profile)

on 21 Sep 2012
Edited by Wayne King

Wayne King (view profile)

on 21 Sep 2012
Accepted answer

You can just do:

      mean(x)
      Ex = norm(x,2)^2  % the energy 
      Px = 1/numel(x)*norm(x,2)^2 % power

If you don't want to use norm(), you just use sum()

      Ex = sum(abs(x).^2)
      Px = 1/numel(x)*sum(abs(x).^2)

Note that the RMS of the signal is

      sqrt(Px)

The Signal Processing Toolbox implements this as rms()

2 Comments

Passband Modulation on 21 Sep 2012

thank you very much, it works well!!

Walter Roberson

Walter Roberson (view profile)

on 18 Dec 2013

pinak parida commented,

power ,energy of a signal how norm works to be check?
Wayne King

Wayne King (view profile)

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