Convex function than convex or strictly convex functions, since they are a smaller class. Like strictly convex functions, strongly convex functions have unique minima on compact sets. A uniformly convex function, with modulus formula_70, is a function that, for all "x", "y" in the domain and , satisfies where formula_70 is a function that is non-negative and vanishes only at 0. This is a generalization of the concept of strongly convex function; by taking formula_73 we recover the definition of strong convexity. Convex function In mathematics, a real-valued function defined on an "n"-dimensional interval is called convex (or convex downward or concave
Compound refractive lens the order of meters, by using many lenses in series. To minimize the absorption the lens must be made from a material such as aluminium, beryllium, or lithium. CRLs were first demonstrated in the mid-1990s by a group of scientists at the ESRF. They drilled holes in an aluminium block, and achieved focusing in two dimensions. For X-rays a concave lens focuses the X-rays because the index of refraction is slightly below unity. In a CRL of this type the walls between the cylindrical holes act as concave lenses for X-rays traveling perpendicular to the axis of the drilled cylinders.