How Diff. Ranges Affect Fourier Series

In summary, the conversation discusses a general question about a set of questions in a textbook regarding finding the Fourier series of a given function. The questions differ only in the range in which the function is defined, and the conversation explores how this difference will affect the resulting Fourier series. The expert summarizer provides the conclusion that the two functions will result in completely different series due to their different graphs.
  • #1
jegues
1,097
3

Homework Statement



I just have a general question about a set of questions given in my textbook.

Homework Equations





The Attempt at a Solution



The questions are given in sequential order, and they both ask the same thing,

Find the Fourier series of the function f(x).

One question gives,

[tex]f(x) = 3x, \quad 0 < x \leq 2L, \quad f(x+2L) = f(x)[/tex]

The question immeadiatly after gives,

[tex]f(x) = 3x, \quad -L < x \leq L, \quad f(x+2L) = f(x)[/tex]

Note that the only thing that changed in these two questions was the range in which the function is defined.

How is this difference in range, or where the function is defined going to affect the resulting Fourier series?

Is there an obvious conclusion I should be drawing from this?

Thanks again!
 
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  • #2
They are two different functions (draw more than one period). Look at their graphs. For example, the second one is an odd one and the first isn't. You will get completely different series.
 

1. What is a Fourier series and how is it affected by different ranges?

A Fourier series is a mathematical representation of a periodic function as a sum of sine and cosine wave components. The range of the function refers to the interval over which the function is defined. The range can affect the coefficients and the convergence of the Fourier series.

2. How does the range affect the coefficients in a Fourier series?

The range of a function affects the coefficients in a Fourier series because the coefficients are calculated by integrating the function over the given range. If the range is changed, the coefficients will also change, resulting in a different Fourier series.

3. Can changing the range affect the convergence of the Fourier series?

Yes, changing the range can affect the convergence of the Fourier series. The convergence of a Fourier series is determined by the smoothness of the function and the range over which it is defined. If the range is changed, the smoothness of the function may also change, leading to a different rate of convergence.

4. How can a different range impact the accuracy of a Fourier series approximation?

A different range can impact the accuracy of a Fourier series approximation because the range affects the number of terms needed in the series to accurately represent the function. A smaller range may require more terms, while a larger range may require fewer terms. Changing the range can also introduce more or less error in the approximation.

5. Can a change in range affect the applications of Fourier series?

Yes, a change in range can affect the applications of Fourier series. Different ranges may be more suitable for different applications. For example, a smaller range may be better for modeling a periodic function with a high frequency, while a larger range may be better for a lower frequency function. It is important to choose the appropriate range for the desired application to ensure an accurate representation of the function.

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