### Quadric where 1=x = (x1, x2, ..., xD+1) is a row vector, xT is the transpose of x (a column vector), Q is a (D + 1) × (D + 1) matrix and P is a (D + 1)-dimensional row vector and R a scalar constant. The values Q, P and R are often taken to be over real numbers or complex numbers, but a quadric may be defined over any ring. In general, the ...
Found on http://en.wikipedia.org/wiki/Quadric

### Quadric • (n.) A quantic of the second degree. See Quantic. • (n.) A surface whose equation in three variables is of the second degree. Spheres, spheroids, ellipsoids, paraboloids, hyperboloids, also cones and cylinders with circular bases, are quadrics. • (a.) Of or pertaining to the second degree.
Found on http://thinkexist.com/dictionary/meaning/quadric/

### quadric quadric surface noun a curve or surface whose equation (in Cartesian coordinates) is of the second degree
Found on https://www.encyclo.co.uk/local/20974

### Quadric [projective geometry] There are generalizations of quadrics: quadratic sets. A quadratic set is a set of points of a projective plane/space, which bears the same geometric properties as a quadric: any line intersects a quadratic set in no or 1 or two lines or is containt in the set. ...
Found on http://en.wikipedia.org/wiki/Quadric_(projective_geometry)

### Quadric Quad'ric adjective (Math.) Of or pertaining to the second degree.
Found on http://www.encyclo.co.uk/webster/Q/1

### Quadric Quad'ric noun (a) (Alg.) A quantic of the second degree. See Quantic . (b) (Geom.) A surface whose equation in three variables is of the second degree. Spheres, spheroids, ellipsoids, paraboloids, hyperboloids, also cones and cylinders with circular bases, are quadri...
Found on http://www.encyclo.co.uk/webster/Q/1

### quadric A surface in three dimensions that is described by equations containing the squares of x, y, and z, but no higher powers of them. Examples of such surfaces include the sphere, the ellipsoid, the cone, and the cylinder.
Found on http://www.daviddarling.info/encyclopedia/Q/quadric.html

### quadric [n] - a curve or surface whose equation (in Cartesian coordinates) is of the second degree
Found on http://www.webdictionary.co.uk/definition.php?query=quadric
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