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  2. Bessel function - Wikipedia

    en.wikipedia.org/wiki/Bessel_function

    Bessel functions describe the radial part of vibrations of a circular membrane.. Bessel functions, named after Friedrich Bessel who was the first to systematically study them in 1824, [1] are canonical solutions y(x) of Bessel's differential equation + + = for an arbitrary complex number, which represents the order of the Bessel function.

  3. Sinc function - Wikipedia

    en.wikipedia.org/wiki/Sinc_function

    It is an interpolating function, i.e., sinc(0) = 1, and sinc(k) = 0 for nonzero integer k. The functions x k (t) = sinc(t − k) (k integer) form an orthonormal basis for bandlimited functions in the function space L 2 (R), with highest angular frequency ω H = π (that is, highest cycle frequency f H = ⁠ 1 / 2 ⁠). Other properties of the ...

  4. Vibration of a circular membrane - Wikipedia

    en.wikipedia.org/wiki/Vibrations_of_a_circular...

    The Bessel function is unbounded for , which results in an unphysical solution to the vibrating drum head problem, so the constant must be null. We will also assume c 1 = 1 , {\displaystyle c_{1}=1,} as otherwise this constant can be absorbed later into the constants A {\displaystyle A} and B {\displaystyle B} coming from T ( t ...

  5. Sombrero function - Wikipedia

    en.wikipedia.org/wiki/Sombrero_function

    Sombrero function 3D. A sombrero function (sometimes called besinc function or jinc function [1]) is the 2-dimensional polar coordinate analog of the sinc function, and is so-called because it is shaped like a sombrero hat. This function is frequently used in image processing. [2]

  6. Ringing artifacts - Wikipedia

    en.wikipedia.org/wiki/Ringing_artifacts

    The sinc function, the impulse response for an ideal low-pass filter, illustrating ringing for an impulse. The Gibbs phenomenon, illustrating ringing for a step function.. By definition, ringing occurs when a non-oscillating input yields an oscillating output: formally, when an input signal which is monotonic on an interval has output response which is not monotonic.

  7. Airy disk - Wikipedia

    en.wikipedia.org/wiki/Airy_disk

    where is the maximum intensity of the pattern at the Airy disc center, is the Bessel function of the first kind of order one, = / is the wavenumber, is the radius of the aperture, and is the angle of observation, i.e. the angle between the axis of the circular aperture and the line between aperture center and observation point.

  8. Point spread function - Wikipedia

    en.wikipedia.org/wiki/Point_spread_function

    In addition, a uniform function over a circular area (in one FT domain) corresponds to J 1 (x)/x in the other FT domain, where J 1 (x) is the first-order Bessel function of the first kind. That is, a uniformly-illuminated circular aperture that passes a converging uniform spherical wave yields an Airy disk image at the focal plane.

  9. Kaiser window - Wikipedia

    en.wikipedia.org/wiki/Kaiser_window

    A related window function is the Kaiser–Bessel-derived (KBD) window, which is designed to be suitable for use with the modified discrete cosine transform (MDCT). The KBD window function is defined in terms of the Kaiser window of length N+1, by the formula: