Help finding fourier coefficient

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SUMMARY

The discussion focuses on calculating the Nth degree Fourier polynomial for the function f(x) = e^x over the interval from -π to π. The key equation used is ak = (1/π) ∫ e^x cos(kx) dx from -π to π, where integration by parts is employed. The user encounters difficulties with the recursive nature of the integral but is advised to utilize a specific trick that simplifies the process after two iterations. The final answer involves combining the original integral with a modified term derived from integration by parts.

PREREQUISITES
  • Understanding of Fourier series and Fourier coefficients
  • Proficiency in integration techniques, particularly integration by parts
  • Familiarity with exponential functions and trigonometric identities
  • Knowledge of definite integrals and their properties
NEXT STEPS
  • Study the method of integration by parts in detail
  • Learn about Fourier series convergence and properties
  • Explore examples of Fourier coefficients for different functions
  • Investigate the application of Fourier polynomials in signal processing
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Students studying calculus, particularly those focusing on Fourier analysis, as well as educators looking to enhance their teaching methods for integration techniques.

Kuma
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Homework Statement



Trying to find the Nth degree Fourier polynomial of

f(x) =e^x for x between -pi to pi.


Homework Equations





The Attempt at a Solution



I'm trying to calculate ak which is given by

1/∏ ∫e^x cos kx dx from -∏ to ∏

I'm getting stuck here trying to use integration by parts. The integral in integration by parts is basically recursive no matter what I set for u or dv.
 
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It's recursive but you only need to do two iterations due to a nice trick which your calculus teacher did you a disservice if he/she didn't teach it to you.

You'll end up with a second copy of the original integral, which you can then combine with the original one. Try it and if you get stuck, post what you have and I'll give you a hint.
 
Hmm I looked at the example. I kind of get it but my answer is a bit off. This is for the definite integral. I'm getting a k^2 e^x cos kx for the second term of the answer. Everything else is the same. The answer is

A2I3I.png
 

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