Fourier series, is this valid?

In summary, the conversation discusses the validity of calculating the x derivative of a Fourier transform and using it to obtain the displacement of a wave in a beam. The inverse Fourier transform can be used to calculate the displacement and the question is whether it is valid to calculate the x derivative and then do an inverse Fourier transform to obtain the displacement derivative. The expert sees no issue with this approach.
  • #1
Trevorman
22
2
Hi, I have a Fourier problem that i do not know if it is valid to do the calculations like this.

The Fourier transform looks like this
##
\hat{v}(x,\omega) = \frac{\hat{F}(\omega)}{4(EI)^{\frac{1}{4}}i \omega^{\frac{3}{2}}(\rho A)^{\frac{3}{4}}}\left[ e^{-i\left[\omega^2 \frac{\rho A}{EI} \right]^{\frac{1}{4}}x} -ie^{-\left[\omega^2 \frac{\rho A}{EI} \right]^{\frac{1}{4}}x} \right]##

and is the Fourier transform of a displacement for a wave in a beam.
The inverse Fourier transform of this equation is the displacement and is displayed below

##v(x,t)= \sum_n\hat{v} \cdot e^{i\omega t}##

What I want to calculate is the x derivative of ##v(x,t)##. Is it valid to calculate ##\frac{\partial \hat{v}}{\partial x}## and do a inverse Fourier transform to get ##v^\prime(x,t)##

In other words, is this valid
## v^\prime(x,t) = \sum_n \hat{v}^\prime \cdot e^{i \omega t}##
 
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  • #2
I don't see any problem with what you wrote.
 
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Likes Trevorman

Related to Fourier series, is this valid?

1. What is a Fourier series?

A Fourier series is a mathematical representation of a periodic function as a sum of sine and cosine functions. It is named after French mathematician Joseph Fourier and is widely used in signal processing and other areas of science and engineering.

2. How is the validity of a Fourier series determined?

A Fourier series is considered valid if the function being represented is periodic and has a finite number of discontinuities within one period. The series may also be truncated, or cut off at a certain number of terms, to improve accuracy.

3. Can any function be represented by a Fourier series?

No, not all functions can be represented by a Fourier series. The function must be periodic and have a finite number of discontinuities within one period. Additionally, some functions may require an infinite number of terms in the series to accurately represent them.

4. How is a Fourier series used in practical applications?

Fourier series are commonly used in signal processing, such as in audio and image compression. They are also used in solving differential equations and in the analysis of periodic phenomena in physics and engineering.

5. What is the relationship between Fourier series and Fourier transforms?

A Fourier transform is a mathematical operation that decomposes a function into its constituent frequencies. A Fourier series is a specific type of Fourier transform that is used for periodic functions. Both are commonly used in signal processing and other areas of science and engineering.

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