Help finding fourier coefficient

In summary, the conversation is about finding the Nth degree Fourier polynomial of f(x) = e^x for x between -pi to pi. The person is trying to calculate ak using integration by parts, but is getting stuck and asks for help. The other person explains a trick to simplify the process and gives the final answer as a0 = 1, ak = k^2 + 1 for k > 0.
  • #1
Kuma
134
0

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.
 
Physics news on Phys.org
  • #2
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.
 
  • #3
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
 

FAQ: Help finding fourier coefficient

What is a Fourier coefficient?

A Fourier coefficient is a mathematical term used in the field of signal processing and analysis. It represents the contribution of a specific frequency component to a signal or function. In other words, it measures how much a particular frequency is present in a given signal.

How are Fourier coefficients calculated?

Fourier coefficients are calculated using a mathematical tool called the Fourier transform. This involves decomposing a signal into its individual frequency components and determining the amplitude and phase of each component. The coefficients are then calculated using these values.

What is the significance of Fourier coefficients?

Fourier coefficients are important in understanding and analyzing signals and functions. They allow us to identify the frequency components present in a signal and how much each component contributes to the overall signal. This information is used in various applications such as image and sound processing, data compression, and pattern recognition.

How are Fourier coefficients used in real-world applications?

Fourier coefficients have a wide range of applications in various fields. In engineering, they are used in designing filters, antennas, and other systems that involve signal processing. In physics, they are used in understanding wave phenomena. They are also used in medical imaging, speech recognition, and many other areas of science and technology.

What are some challenges in finding Fourier coefficients?

One of the main challenges in finding Fourier coefficients is dealing with non-periodic signals or signals with discontinuities. In these cases, the traditional Fourier transform may not be applicable, and alternative methods like the Fourier series or the Laplace transform may be used. Another challenge is dealing with noisy signals, which can affect the accuracy of the coefficients and require advanced techniques for noise reduction.

Back
Top