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# Encyclopedia

In signal processing:

In mathematics:

• Quadrature: Solving an integral analytically, cf Symbolic integration. Refers to a geometrical interpretation of the word.
• Numerical integration, the numerical calculation of the area under a curve, or more generally, using numerical integration to calculate a definite integral
• Quadrature of the circle (also squaring the circle), in geometry, the problem of constructing a square and circle of equal area, impossible using only an unmarked straight-edge and compass
• Summing in quadrature means summing the squares of numbers, then taking the square root, as used in error analysis
• The Quadrature of the Parabola, a treatise by Archimedes
• Gaussian quadrature, a special case of numerical integration, named after Carl Friedrich Gauss

• In motion control, quadrature encoder is a rotary encoder or linear encoder giving both the relative position and the direction of motion of a shaft
• In astronomy, quadrature occurs when two celestial bodies appear 90° apart from one another as viewed from a third celestial body. As an example, the Moon and the Sun are in quadrature with respect to the Earth when the Moon is in its exact first quarter or last quarter phases. The symbol for astronomical quadrature is a hollow square

# 1911 encyclopedia

Up to date as of January 14, 2010

### From LoveToKnow 1911

QUADRATURE (from Lat. quadratura, a making square), in astronomy, that aspect of a heavenly body in which it makes a right angle with the direction of the sun; applied especially to the apparent position of a planet, or of the moon at first and last quarters. In mathematics, quadrature is the determination of a square equal to the area of a curve or other figure.