crossratio

A special number associated with an ordered quadruple of collinear points, particularly points on a projective line, and preserved by the fractional linear transformations.Syn: anharmonic ratio, double ratio
Wikipedia foundation.
Look at other dictionaries:
cross ratio — cross ratio, adj. Geom. a ratio relating four points in the real or complex plane. Also called anharmonic ratio. [1880 85] * * * ▪ mathematics in projective geometry, ratio that is of fundamental importance in characterizing projections. In a… … Universalium
Crossratio — D is the harmonic conjugate of C with respect to A and B In geometry, the cross ratio, also called double ratio and anharmonic ratio, is a special number associated with an ordered quadruple of collinear points, particularly points on a… … Wikipedia
cross ratio — noun Etymology: cross (III) : an anharmonic ratio in mathematics * * * cross ratio, adj. Geom. a ratio relating four points in the real or complex plane. Also called anharmonic ratio. [1880 85] … Useful english dictionary
crossratio — cross raˈtio noun Of four points in a range, or rays in a pencil, the quotient of the positions ratios of two with respect to the other two • • • Main Entry: ↑cross … Useful english dictionary
Cross listing — of one company on multiple exchanges should not be confused with dual listed companies, where two distinct companies with separate stocks listed on different exchanges function as one company. Cross listing of shares is when a firm lists its… … Wikipedia
Crosssectional study — Cross sectional studies (also known as Cross sectional analysis) form a class of research methods that involve observation of all of a population, or a representative subset, at one specific point in time. They differ from case control studies in … Wikipedia
Crossvalidation (statistics) — Cross validation, sometimes called rotation estimation,[1][2][3] is a technique for assessing how the results of a statistical analysis will generalize to an independent data set. It is mainly used in settings where the goal is prediction, and… … Wikipedia
Crossflow turbine — Cross flow turbine. Image credit; European Communities, Layman s Guidebook (on how to develop a small hydroelectric site) A cross flow turbine, Banki Michell turbine, or Ossberger turbine[1] is a water turbine developed by the Australian Anthony… … Wikipedia
Cross elasticity of demand — Economics … Wikipedia
Cross section (physics) — A cross section is the effective area which governs the probability of some scattering or absorption event. Together with particle density and path length, it can be used to predict the total scattering probability via the Beer Lambert law. In… … Wikipedia