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PostPosted: Wed Sep 09, 2015 8:45 pm 
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I know, i know it's an off topic thing, but i think there are enough people here to understand this. So i decided to post it here.
Anyway if ADMIN wants to remove it it's OK and will search a dsp or math forum, but i like this one.

I'm learning with a nice DSP book and talking about how to obtain "mean" leds you to this sum:

Image

And THEN it says it must be interpreted as:

Image

So why is 1/N there in the first screenshot? Doesn't it mean 1 DIVIDED by N? or what?

Sorry the noob thing. :oops:

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PostPosted: Wed Sep 09, 2015 8:55 pm 
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Yes 1 over N is 1 divided by N.

Sigma (Σ) basically means the sum of a for loop. For i = 0 to N - 1, calculate xi and add it to the total. Once you've got that, multiply by (1/N), which is the same as dividing by N.

The second picture replaces the Sigma notation with the series it represents.

On the right side of the sigma, you could have something more complicated, often something that is a function in terms of the index (in this case i.


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PostPosted: Wed Sep 09, 2015 9:19 pm 
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Thanks now it's much clear!!!

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