Describe FFT: Properties/Frequency Needed

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In summary, the conversation discusses the use of a fast Fourier transform (FFT) and its properties and frequency. It is mentioned that the image being discussed is a 2D FFT and there is a question about how to use libraries to compute a discrete Fourier transform (DFT) in C++. There is also a request for help with using FFT to compute a numerical Fourier transform of a bessel function.
  • #1
mgberlin
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Could somone possibly describe this http://home.bak.rr.com/berlin/088821368-guess1.jpg FFT. I need to know the properties and frequency. Thanks for anyone's time who helps.

(BTW, if this is in the wrong forum, I could use some redirection).
 
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  • #2
That's a fast Fourier transform?

I don't see any axes... what are we looking at? :confused:
 
  • #3
Psst... it's a 2D FFT. (I don't know what it means though.)

- Warren
 
  • #4
how can i make use of libraries available to do those in C++ to compute DFT

also I would be so grateful if you could help me for numerical fourir transform of bessel function using FFT
 

1. What is FFT and what does it stand for?

FFT stands for Fast Fourier Transform. It is a mathematical algorithm used to efficiently calculate the discrete Fourier Transform (DFT) of a sequence or signal. It is commonly used in signal processing and data analysis.

2. What are the properties of FFT?

The main properties of FFT include:

  • Efficiency: FFT is a fast algorithm that can compute the DFT in a significantly shorter time compared to traditional methods.
  • Symmetry: FFT assumes that the input signal is periodic, which means it has a certain symmetry that allows for faster computation.
  • Accuracy: FFT is an exact algorithm, meaning it produces the exact DFT values without any approximation.
  • Linearity: FFT is a linear operation, meaning the output of the DFT is a linear combination of the input signal.

3. What frequency is needed for FFT?

FFT can be used for any frequency, as long as the input signal is periodic. However, it is most commonly used for signals with high frequencies or a large number of data points. The more data points there are, the more accurate the FFT results will be.

4. How does FFT work?

FFT works by breaking down a signal into its individual frequency components, using a divide-and-conquer approach. It divides the signal into smaller segments, calculates their DFTs, and then combines them to get the final DFT of the entire signal. This process is repeated recursively until the desired accuracy is achieved.

5. Can FFT be used for non-periodic signals?

No, FFT can only be used for periodic signals, as it assumes that the input signal is repeating infinitely. For non-periodic signals, other methods such as the Discrete Cosine Transform (DCT) or Wavelet Transform can be used.

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