Stilb (unit) Stilb (unit) The stilb (sb) is the CGS unit of luminance for objects that are not self-luminous. It is equal to one candela per square centimeter or 10 nits (candelas per square meter). The name was coined by the French physicist André Blondel around 1920. It comes from the Greek word "stilbein" meaning "to glitter". It was in common use in Europe up to World War I. In North America self-explanatory terms such as candle per square inch and candle per square meter were more common. The unit has since largely been replaced by the SI unit: candela per square
Curvature of a measure points "x", "y" and "z" in R, let "R"("x", "y", "z") be the radius of the Euclidean circle that joins all three of them, or +∞ if they are collinear. The Menger curvature "c"("x", "y", "z") is defined to be with the natural convention that "c"("x", "y", "z") = 0 if "x", "y" and "z" are collinear. It is also conventional to extend this definition by setting "c"("x", "y", "z") = 0 if any of the points "x", "y" and "z" coincide. The Menger-Melnikov curvature "c"("μ") of "μ" is defined to be More generally, for "α" ≥ 0, define "c"("μ")