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  2. Spectrum continuation analysis - Wikipedia

    en.wikipedia.org/wiki/Spectrum_continuation_analysis

    Spectrum continuation analysis (SCA) is a generalization of the concept of Fourier series to non-periodic functions of which only a fragment has been sampled in the time domain. Recall that a Fourier series is only suitable to the analysis of periodic (or finite-domain) functions f(x) with period 2π. It can be expressed as an infinite series ...

  3. Quasicrystal - Wikipedia

    en.wikipedia.org/wiki/Quasicrystal

    There are several ways to mathematically define quasicrystalline patterns. One definition, the "cut and project" construction, is based on the work of Harald Bohr (mathematician brother of Niels Bohr). The concept of an almost periodic function (also called a quasiperiodic function) was studied by Bohr, including work of Bohl and Escanglon. [47]

  4. Trapezoidal rule - Wikipedia

    en.wikipedia.org/wiki/Trapezoidal_rule

    The trapezoidal rule converges rapidly for periodic functions. This is an easy consequence of the Euler-Maclaurin summation formula , which says that if f {\displaystyle f} is p {\displaystyle p} times continuously differentiable with period T {\displaystyle T} ∑ k = 0 N − 1 f ( k h ) h = ∫ 0 T f ( x ) d x + ∑ k = 1 ⌊ p / 2 ⌋ B 2 k ...

  5. Spectral density estimation - Wikipedia

    en.wikipedia.org/wiki/Spectral_density_estimation

    General mathematical techniques for analyzing non-periodic functions fall into the category of Fourier analysis. The Fourier transform of a function produces a frequency spectrum which contains all of the information about the original signal, but in a different form.

  6. Amplitude - Wikipedia

    en.wikipedia.org/wiki/Amplitude

    The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of amplitude (see below), which are all functions of the magnitude of the differences between the variable's extreme values. In older texts, the phase of a periodic function is sometimes called the amplitude. [1]

  7. Rule 30 - Wikipedia

    en.wikipedia.org/wiki/Rule_30

    Rule 30 is so named because 30 is the smallest Wolfram code which describes its rule set (as described below). The mirror image, complement, and mirror complement of Rule 30 have Wolfram codes 86, 135, and 149, respectively.

  8. Periodic function - Wikipedia

    en.wikipedia.org/wiki/Periodic_function

    A periodic function, also called a periodic waveform (or simply periodic wave), is a function that repeats its values at regular intervals or periods. The repeatable part of the function or waveform is called a cycle . [ 1 ]

  9. List of periodic functions - Wikipedia

    en.wikipedia.org/wiki/List_of_periodic_functions

    This is a list of some well-known periodic functions. The constant function f (x) = c, where c is independent of x, is periodic with any period, but lacks a fundamental period. A definition is given for some of the following functions, though each function may have many equivalent definitions.