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Odd summation without specific value

AL_10844378
3-Visitor

Odd summation without specific value

Hi 
I want to plot this summation. I would like to do it as an 'odd summation', were I don't want it to process n=2. Is there an easy solution for this problem?

AL_10844378_0-1702737598730.png

 



1 ACCEPTED SOLUTION

Accepted Solutions

I would have interpreted "odd" so that the sums should run only over the odd numbers 1,3,5,... so n=2 would be no problem at all.

 

What do you mean by "plotting the sum"?

 

If your sum should run from 1 up to infinity (including the even numbers) I see two ways to avoid the case n=2:

1) use something like    if(n=2, 0, <the expression you'd like to sum up>)    in the sum

2) Let the sum run from 3 up to infinity and add the result you get for n=1

 

Nonetheless I would expect that n should only take od numbers as otherwise (-1)^((n+1)/2) = imaginary unit .

 

So maybe you are looking for something like this:

Werner_E_1-1702739022904.png

 

 

 

 

View solution in original post

4 REPLIES 4

I would have interpreted "odd" so that the sums should run only over the odd numbers 1,3,5,... so n=2 would be no problem at all.

 

What do you mean by "plotting the sum"?

 

If your sum should run from 1 up to infinity (including the even numbers) I see two ways to avoid the case n=2:

1) use something like    if(n=2, 0, <the expression you'd like to sum up>)    in the sum

2) Let the sum run from 3 up to infinity and add the result you get for n=1

 

Nonetheless I would expect that n should only take od numbers as otherwise (-1)^((n+1)/2) = imaginary unit .

 

So maybe you are looking for something like this:

Werner_E_1-1702739022904.png

 

 

 

 

Hi Werner
Is there a way where I can make a summation of ONLY the odd numbers n=1,3,5,7..? That would solve my problem
I tried your second option (as I could not find a way to do the first option), but it would be nice if there was a more pretty way to do it? 🙂

AL_10844378_0-1702739321594.png

 

 


@AL_10844378 wrote:

Hi Werner
Is there a way where I can make a summation of ONLY the odd numbers n=1,3,5,7..? That would solve my problem


Look at my example at the end of my previous answer.

 

k runs from 1 to inf and instead of n I use (2*k-1) which the are the odd numbers 1,3,5,...

ttokoro
20-Turquoise
(To:AL_10844378)

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