Fourier Series for ex and Parseval Identity | Simple Problem Solution

Click For Summary
SUMMARY

The discussion focuses on finding the Fourier series for the function \( e^x \) over the interval (-1, 1) and deriving the Parseval identity. The correct formula for the Fourier coefficients \( c_n \) is established as \( c_n = \frac{1}{2}\int_{-1}^{1} e^x e^{-i n x} dx \), with the period \( P = 2 \). A participant pointed out an error in the initial coefficient formula, clarifying that for a period \( P = 2 \), the coefficients should be calculated using \( c_n = \frac{1}{2}\int_{-1}^{1} e^x e^{-i n x} dx \).

PREREQUISITES
  • Understanding of Fourier series and Fourier coefficients
  • Knowledge of complex exponentials and integration techniques
  • Familiarity with the Parseval identity in Fourier analysis
  • Basic proficiency in calculus, particularly integration over defined intervals
NEXT STEPS
  • Study the derivation of Fourier series for different functions
  • Learn about the application of Parseval's theorem in signal processing
  • Explore the properties of complex exponentials in Fourier analysis
  • Investigate numerical methods for approximating Fourier coefficients
USEFUL FOR

Students studying advanced calculus, mathematicians focusing on Fourier analysis, and anyone interested in applying Fourier series to solve real-world problems in engineering and physics.

springo
Messages
125
Reaction score
0

Homework Statement


Find the Fourier series for ex for x in (-1,1).
Find the Parseval identity.

Homework Equations



The Attempt at a Solution


[tex]c_{n}=\frac{1}{2}\int_{-1}^{1}e^{x}e^{-i n x}dx[/tex]
Where cn are the coefficients of the Fourier series.

I tried plotting
[tex]\sum_{k=-\infty}^{\infty}c_{n}e^{i n x}[/tex]
together with ex and it doesn't seem to be correct...

Thank you for your help!
 
Last edited:
Physics news on Phys.org
For starters, your formula for cn is wrong. For period P = 2p:

[tex]c_n = \frac 1 {2p}\int_{-p}^p f(x) e^{\frac {i n \pi}{p}}dx[/tex]

In your problem p = 1.
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
1
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
3
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
Replies
3
Views
2K