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  2. Discrete Fourier series - Wikipedia

    en.wikipedia.org/wiki/Discrete_Fourier_series

    In digital signal processing, a discrete Fourier series (DFS) is a Fourier series whose sinusoidal components are functions of discrete time instead of continuous time. A specific example is the inverse discrete Fourier transform (inverse DFT).

  3. Discrete Fourier transform - Wikipedia

    en.wikipedia.org/wiki/Discrete_Fourier_transform

    In mathematics, the discrete Fourier transform (DFT) converts a finite sequence of equally-spaced samples of a function into a same-length sequence of equally-spaced samples of the discrete-time Fourier transform (DTFT), which is a complex-valued function of frequency. The interval at which the DTFT is sampled is the reciprocal of the duration ...

  4. Discrete-time Fourier transform - Wikipedia

    en.wikipedia.org/wiki/Discrete-time_Fourier...

    The lower right corner depicts samples of the DTFT that are computed by a discrete Fourier transform (DFT). The utility of the DTFT is rooted in the Poisson summation formula, which tells us that the periodic function represented by the Fourier series is a periodic summation of the continuous Fourier transform: [b]

  5. Fourier series - Wikipedia

    en.wikipedia.org/wiki/Fourier_series

    A Fourier series (/ ˈ f ʊr i eɪ,-i ər / [1]) is an expansion of a periodic function into a sum of trigonometric functions. The Fourier series is an example of a trigonometric series. [2] By expressing a function as a sum of sines and cosines, many problems involving the function become easier to analyze because trigonometric functions are ...

  6. Fourier transform - Wikipedia

    en.wikipedia.org/wiki/Fourier_transform

    [note 3] Still further generalization is possible to functions on groups, which, besides the original Fourier transform on R or R n, notably includes the discrete-time Fourier transform (DTFT, group = Z), the discrete Fourier transform (DFT, group = Z mod N) and the Fourier series or circular Fourier transform (group = S 1, the unit circle ≈ ...

  7. Fourier analysis - Wikipedia

    en.wikipedia.org/wiki/Fourier_analysis

    Fourier series; Discrete-time Fourier transform; ... The inverse transform, known as Fourier series, is a representation of () in terms of a summation of ...

  8. Discrete frequency domain - Wikipedia

    en.wikipedia.org/wiki/Frequency_domain

    The discrete-time Fourier transform, on the other hand, maps functions with discrete time (discrete-time signals) to functions that have a continuous frequency domain. [ 2 ] [ 3 ] A periodic signal has energy only at a base frequency and its harmonics; thus it can be analyzed using a discrete frequency domain.

  9. DFT matrix - Wikipedia

    en.wikipedia.org/wiki/DFT_matrix

    In this case, if we make a very large matrix with complex exponentials in the rows (i.e., cosine real parts and sine imaginary parts), and increase the resolution without bound, we approach the kernel of the Fredholm integral equation of the 2nd kind, namely the Fourier operator that defines the continuous Fourier transform. A rectangular ...