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  2. K-13 (missile) - Wikipedia

    en.wikipedia.org/wiki/K-13_(missile)

    In 1962, work started on a semi-active radar homing (SARH) version for high-altitude use, the K-13R (R-3R or Object 320) with 8 km range, [citation needed] similar to the little-used US Navy AIM-9C Sidewinder (carried by the F-8 Crusader). This took longer to develop, and while its first launches were in 1963, it did not enter service until ...

  3. Fourier transform - Wikipedia

    en.wikipedia.org/wiki/Fourier_transform

    The Heisenberg group is a certain group of unitary operators on the Hilbert space L 2 (R) of square integrable complex valued functions f on the real line, generated by the translations (T y f)(x) = f (x + y) and multiplication by e i2πξx, (M ξ f)(x) = e i2πξx f (x).

  4. List of unusual units of measurement - Wikipedia

    en.wikipedia.org/wiki/List_of_unusual_units_of...

    [25] [26] The standard FIFA football pitch for international matches is 105 m (344 ft) long by 68 m (223 ft) wide (7,140 m 2 or 0.714 ha or 1.76 acres); FIFA allows for a variance of up to 5 m (16.4 ft) in length in either direction and 7 m (23.0 ft) more or 4 m (13.1 ft) less in width (and larger departures if the pitch is not used for ...

  5. Orders of magnitude (length) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(length)

    The kilometre (SI symbol: km) is a unit of length in the metric system equal to 1 000 meters (10 3 m). To help compare different orders of magnitude , this section lists lengths between 1 kilometer and 10 kilometers (10 3 and 10 4 meters ).

  6. Discrete Fourier transform - Wikipedia

    en.wikipedia.org/wiki/Discrete_Fourier_transform

    Second, if the are real numbers, then () is real as well. In contrast, the most obvious trigonometric interpolation polynomial is the one in which the frequencies range from 0 to N − 1 {\displaystyle N-1} (instead of roughly − N / 2 {\displaystyle -N/2} to + N / 2 {\displaystyle +N/2} as above), similar to the inverse DFT formula.

  7. Orders of magnitude (pressure) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(pressure)

    Pressure due to direct impact of a strong breeze (~28 mph or 45 km/h) [27] [28] [31] 120 Pa Pressure from the weight of a U.S. quarter lying flat [32] [33] 133 Pa 1 torr ≈ 1 mmHg [34] ±200 Pa ~140 dB: Threshold of pain pressure level for sound where prolonged exposure may lead to hearing loss [citation needed] ±300 Pa ±0.043 psi

  8. Kilometre - Wikipedia

    en.wikipedia.org/wiki/Kilometre

    There are two common pronunciations for the word. [1]/ ˈ k ɪ l ə m iː t ər,-l oʊ-/ / k ɪ ˈ l ɒ m ɪ t ər / The first pronunciation follows a pattern in English whereby SI units are pronounced with the stress on the first syllable (as in kilogram, kilojoule and kilohertz) and the pronunciation of the actual base unit does not change irrespective of the prefix (as in centimetre ...

  9. Closed manifold - Wikipedia

    en.wikipedia.org/wiki/Closed_manifold

    The only connected one-dimensional example is a circle. The sphere, torus, and the Klein bottle are all closed two-dimensional manifolds. The real projective space RP n is a closed n-dimensional manifold. The complex projective space CP n is a closed 2n-dimensional manifold. [1] A line is not closed because it is not compact