Determining Terms in $\sum_{n=-N}^{N}|e^{J\frac{\pi}{4}n}|^2$

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Discussion Overview

The discussion revolves around determining the number of terms in the summation $\sum_{n=-N}^{N}|e^{J\frac{\pi}{4}n}|^2$. Participants explore the reasoning behind the conclusion that there are $2N + 1$ terms in this summation, focusing on the range of values for \( n \) from \(-N\) to \(N\).

Discussion Character

  • Exploratory, Homework-related

Main Points Raised

  • Some participants assert that the total number of terms is \(2N + 1\) based on counting the values of \(n\) from \(-N\) to \(N\).
  • One participant explains their reasoning by breaking down the count into negative values, zero, and positive values, leading to the conclusion of \(2N + 1\).
  • Another participant questions the choice of the range, suggesting alternative ranges such as \(-N\) to \(-2\), indicating confusion about the counting method.
  • Participants clarify that the range includes all integers from \(-N\) to \(N\), which encompasses \(N\) negative values, zero, and \(N\) positive values.

Areas of Agreement / Disagreement

Participants generally agree on the conclusion that there are \(2N + 1\) terms, but there is some confusion regarding the counting method and the choice of range, indicating a lack of consensus on the reasoning process.

Contextual Notes

Some participants express uncertainty about the counting method and the implications of different ranges, which may affect their understanding of the total number of terms.

Drain Brain
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I just want to know how do I determine the number of terms will be in this summation. The answer to this 2N+1 terms. I can only arrive at preliminary steps of solving this. can you tell why 2N+1 is the number of terms? I know that the magnitude of complex exponential function squared would result to one.

$\sum_{n=-N}^{N}|e^{J\frac{\pi}{4}n}|^2$
 
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Drain Brain said:
I just want to know how do I determine the number of terms will be in this summation. The answer to this 2N+1 terms. I can only arrive at preliminary steps of solving this. can you tell why 2N+1 is the number of terms? I know that the magnitude of complex exponential function squared would result to one.

$\sum_{n=-N}^{N}|e^{J\frac{\pi}{4}n}|^2$

as n is from -N to N the total number of terms is N ( -N to -1) + 1 ( zero) + N ( 1 to N) = 2N + 1

Within parenthesis I have mentioned the range
 
kaliprasad said:
as n is from -N to N the total number of terms is N ( -N to -1) + 1 ( zero) + N ( 1 to N) = 2N + 1

Within parenthesis I have mentioned the range

Hi kaliprasad! How did you choose the range?
 
Drain Brain said:
Hi kaliprasad! How did you choose the range?

In the sum that is (sigma) n is from -N to N and hence the range
 
kaliprasad said:
In the sum that is (sigma) n is from -N to N and hence the range

why it is only -N to -1, 0, and 1 to N? I'm thinking of other ranges like -N to -2 etc.. I'm confused. Please help.
 
Drain Brain said:
why it is only -N to -1, 0, and 1 to N? I'm thinking of other ranges like -N to -2 etc.. I'm confused. Please help.

Sorry for the confusion. I counted the number of -ve values, positive values and zero separately. from -N to +N it is 2N+1 values
 

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