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fft [Tue Oct 26 10:59:32 2010] Alexander |
fft [Thu Jan 14 17:14:11 2021] Alexander |
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- | ====== Fast Fourier Transform (FFT) (Pro edition only) ====== | + | ====== Fast Fourier Transform (FFT) ====== |
Open Table or Figure or Plot with initial data and use '' | Open Table or Figure or Plot with initial data and use '' | ||
Fast Fourier transform algorithm computes discrete Fourier transform exactly and is used to considerably speed up the calculations.\\ Note that FFT is not an approximate method of calculation. | Fast Fourier transform algorithm computes discrete Fourier transform exactly and is used to considerably speed up the calculations.\\ Note that FFT is not an approximate method of calculation. | ||
- | MagicPlot uses the algorithm of FFT that does not necessarily require the number of points //N// to be an integer power of 2, though in case of power of 2 evaluation time of the FFT algorithm is less. MagicPlot uses [[http://www.netlib.org/ | + | {{:fft.png?nolink|}} |
- | | {{:fft1.png|FFT of table columns dialog}} | + | ===== Parameters ===== |
+ | |||
+ | ^ Sampling Interval | ||
+ | ^ Real, \\ Imaginary | ||
+ | ^ Forward / \\ Inverse | ||
+ | ^ 1/N in forward transform | ||
+ | ^ Center zero frequency | ||
+ | |||
+ | ===== Algorithm ===== | ||
+ | |||
+ | MagicPlot uses the algorithm of FFT that does not necessarily require the number | ||
- | ===== Formulas ===== | ||
==== Discrete Fourier Transform Formulas ==== | ==== Discrete Fourier Transform Formulas ==== | ||
- | By default MagicPlot uses ' | + | By default MagicPlot uses ' |
^ Factor −1 (Default) | ^ Factor −1 (Default) | ||
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Here // | Here // | ||
- | Note: If you expect to get the original data when doing a inverse FFT of forward FFT set the '' | + | Note: if you expect to get the original data when doing an inverse FFT of forward FFT, set the '' |
==== Amplitude and Phase Columns Formulas ==== | ==== Amplitude and Phase Columns Formulas ==== | ||
- | <m>Amplitude_n | + | <m>A_n = sqrt{{Re_n}^2 + {Im_n}^2}, |
- | Because of using [[wp> | + | Because of using '' |
==== Sampling Column Formulas ==== | ==== Sampling Column Formulas ==== | ||
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* Missing values in the end of the column are ignored. | * Missing values in the end of the column are ignored. | ||
- | ===== Parameters | + | ===== See Also ===== |
- | ^ Sampling Interval | + | |
- | ^ Real, \\ Imaginary | + | |
- | ^ Forward / \\ Inverse | + | |
- | ^ 1/N in forward transform | + | |
- | ^ Center zero frequency | + |