Need some series/ summation help

In summary, the conversation discusses a series with a term involving (-1)^n and a fraction. The question is raised about finding a closed form or representation for the series and suggestions are given, including using a polylogarithm or Dirichlet eta function. There is also some confusion about whether the series converges, but it is clarified that it does converge by comparing it to a similar series.
  • #1
rman144
35
0
[tex]\sum_{n=1}^{\infty}(-1)^{n}\frac{e^{-\frac{1}{nx}}}{n}[/tex]

Where 0<x<oo.

I'm looking for a closed form/ closed representation for this series [I was thinking something like a polylogarithm or dirichlet eta function combination might work].

Any ideas or suggestions would be much appreciated.
 
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  • #2
it does not converge...
 
  • #3
soandos said:
it does not converge...

Sure it does, it differs from [tex]\sum_{n=1}^\infty \frac{(-1)^n}{n}[/tex] by an absolutely convergent series.
 
  • #4
If (-1)^n is being raised to [tex]\frac{e^{-\frac{1}{nx}}}{n}[/tex], i do not believe it converges. (it can also be simplified, the n's go away). please clarify what you mean.
 
  • #5
I understand the confulsion. If you read the TeX code included, you can see what was actually written. The term to be summed is [itex](-1)^n[/itex] times a fraction:
[tex]\sum_{n=1}^{\infty}\;(-1)^{n}\left(\frac{e^{-\frac{1}{nx}}}{n}\right)[/tex]
 
  • #6
g_edgar said:
I understand the confulsion. If you read the TeX code included, you can see what was actually written. The term to be summed is [itex](-1)^n[/itex] times a fraction:
[tex]\sum_{n=1}^{\infty}\;(-1)^{n}\left(\frac{e^{-\frac{1}{nx}}}{n}\right)[/tex]

Sorry about the confusion. I should have included the brackets as you demonstrated.
 

1. What is the purpose of series and summation in science?

Series and summation are mathematical tools used in science to represent and analyze data in a more concise and manageable way. It allows scientists to identify patterns and trends in large sets of data, and make predictions and conclusions based on the data.

2. How do you determine the sum of a series?

The sum of a series can be determined by adding up all the terms in the sequence. This can be done manually by using a calculator or through mathematical formulas and techniques such as the geometric series formula or the telescoping series method.

3. What is the difference between arithmetic and geometric series?

In an arithmetic series, each term is obtained by adding a constant value to the previous term, while in a geometric series, each term is obtained by multiplying a constant value to the previous term. In other words, the difference between consecutive terms is constant in an arithmetic series, while the ratio between consecutive terms is constant in a geometric series.

4. How are series and summation used in real-world applications?

Series and summation are used in a wide range of fields, including physics, chemistry, economics, and engineering. They are used to model and analyze real-world phenomena, such as population growth, radioactive decay, and financial investments.

5. What are some common mistakes to avoid when working with series and summation?

Some common mistakes to avoid include not following the proper order of operations, forgetting to account for negative terms, and not considering the convergence or divergence of a series. It is also important to double-check calculations and use appropriate mathematical techniques for different types of series.

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