# Quadrature

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**Quadrature** may refer to:

## Mathematics

- [Quadrature (mathematics)](/source/Quadrature_(mathematics)), a historic term for the computation of the area of a given plane figure, drawing a square with the same area, an integral or integration - [Squaring the circle](/source/Squaring_the_circle) - *[Quadrature of the Parabola](/source/Quadrature_of_the_Parabola)* - [Quadrature of the hyperbola](/source/Quadrature_of_the_hyperbola)
- [Numerical integration](/source/Numerical_integration), calculating the numerical value of a definite integral, is often called "numerical quadrature" or simply "quadrature" - [Gaussian quadrature](/source/Gaussian_quadrature), a rule for numerical integration
- [Quadrature (differential equations)](/source/Quadrature_(differential_equations)), expressing a differential equation solution in terms of antiderivatives

## Signal processing

- [Addition in quadrature](/source/Addition_in_quadrature), combining the magnitude of uncorrelated signals by taking the square root of the sum of their squares
- [Quadrature phase](/source/Quadrature_phase), oscillations that are said to be *in quadrature* if they are separated in phase by 90° (π/2, or /4)
- [Quadrature component](/source/Quadrature_component) of a composite signal
- [Quadrature filter](/source/Quadrature_filter), the analytic signal of a real-valued filter
- [Quadrature amplitude modulation](/source/Quadrature_amplitude_modulation) (QAM), a modulation method of using both an (in-phase) carrier wave and a 'quadrature' carrier wave that is 90° out of phase with the main, or in-phase, carrier
- [Quadrature phase-shift keying](/source/Quadrature_phase-shift_keying) (QPSK), a phase-shift keying of using four quadrate points on the constellation diagram, equispaced around a circle

## Science

- [Optical phase space quadratures](/source/Optical_phase_space#Quadratures), operators which represent the real and imaginary parts of the complex amplitude
- [Quadrature (astronomy)](/source/Quadrature_(astronomy)), the position of a body (moon or planet) such that its elongation is 90° or 270°; i.e., the body-earth-sun angle is 90°

## Other uses

- [Quadrature encoder](/source/Quadrature_encoder), a device that detects mechanical position changes and direction of movement
- [Illusionistic ceiling painting](/source/Illusionistic_ceiling_painting), sometimes called *quadrature* after the Italian term, *quadratura*
- [La Quadrature du Net](/source/La_Quadrature_du_Net) (Squaring of the Net in French), a French advocacy group that promotes digital rights and freedoms of citizens
- "Quadrature", a song by Squarepusher from the album *[Just a Souvenir](/source/Just_a_Souvenir)*

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Adapted from the Wikipedia article [Quadrature](https://en.wikipedia.org/wiki/Quadrature) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Quadrature?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.