They are called "hermitian quadrics". Equivalently, it is a projective variety, defined as the zero locus of three smooth quadrics. Reye worked on conic sections, quadrics and projective geometry. But the relevant quadrics here are not in general position. An important application of plane sections of quadrics is contour lines of quadrics. Intersections between spheres, cylinders, or other quadrics can be found using quartic equations. In complex projective space all of the nondegenerate quadrics become indistinguishable from each other. There are "generalizations" of quadrics&colon; quadratic sets. In August 2005 Quadrics and STMicroelectronics signed a development agreement. More hidden are circles on other quadrics, such as tri-axial ellipsoids, elliptic cylinders, etc. It was inspired by the closed source Quadrics RMS and shares a similar syntax. The orthogonal system of quadrics used for the ellipsoidal coordinates are confocal quadrics. In "P", an elliptic curve can be obtained as the intersection of two quadrics. These two examples are "quadrics" and are projectively equivalent. For quadrics, formula 32 is always a linear function.