Can 1/a Be Expanded Using Fourier Expansion?

In summary, a user is asking if the term 1/a can be expanded using Fourier expansion and how to do so. Another user clarifies that normally functions are expanded in Fourier series, not numbers, but if f(z)=1/a is considered a constant function, its Fourier series would simply be (1/a)+ 0 sin(z)+ 0 cos(z)+ ... If f(z)=1/z, a Fourier series can be found using standard formulas, but it will not converge at z=0. The user then asks about the solution for f(x)=(1-x/a) after Fourier expansion, to which the response is that the function needs to be periodic to have a Fourier series.
  • #1
kaizen.moto
98
0
Dear all,

Iam just wondering whether the term 1/a can be expanded using Fourier expansion. If it does, please let me know how to to do this.

Thank for any kind help.
 
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  • #2


What do you mean bu "the term 1/a"? Normally, we expand functions in Fourier series, not numbers. Of course, we can think of f(z)= 1/a as the constant function. In that case, the Fourier series is simply (1/a)+ 0 sin(z)+ 0 cos(z)+ ...

If you mean f(z)= 1/z, then, yes, you can find a Fourier series for 1/z using the standard formulas. It will not converge at z= 0, of course.
 
  • #3


How about f(x) = (1 - x/a), what would be the solution after Fourier expansion?
 
  • #4
Any constant is a finite Fourier series with all the sine and cosine terms having 0 coeifficients. There is nothing to calculate.
 
  • #5


kaizen.moto said:
How about f(x) = (1 - x/a), what would be the solution after Fourier expansion?

Your f(x) needs to be periodic to have a FS.
 
  • #6
Moderator's note: I copied several posts from the thread that was started in the Mathematics technical section.
 

1. What is a Fourier expansion?

A Fourier expansion, also known as a Fourier series, is a way to represent a periodic function as a sum of sine and cosine waves. It is named after French mathematician Jean-Baptiste Joseph Fourier, who first introduced the concept in the early 19th century.

2. How is a Fourier expansion useful in mathematics?

A Fourier expansion is useful in mathematics because it allows us to approximate any periodic function with a finite number of terms. This makes it easier to analyze and manipulate complex functions, as well as solve differential equations and other problems.

3. What are the key components of a Fourier expansion?

A Fourier expansion consists of a series of coefficients, known as Fourier coefficients, and a set of basis functions, typically sine and cosine waves. The coefficients determine the amplitude and phase of each basis function, which together form the periodic function being represented.

4. Can a Fourier expansion be used for non-periodic functions?

No, a Fourier expansion can only be used for periodic functions. However, there are other methods, such as the Fourier transform, that can be used to represent non-periodic functions as a sum of sinusoidal functions.

5. Are there any limitations to using Fourier expansions?

While Fourier expansions are a powerful tool in mathematics, they do have some limitations. For example, they may not converge for functions that are discontinuous or have sharp corners. In addition, they may not provide an accurate representation for functions with rapidly changing behavior.

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