Concave function pointwise minimum of two concave functions, i.e. the set of concave functions on a given domain form a semifield. 3. Near a local maximum in the interior of the domain of a function, the function must be concave; as a partial converse, if the derivative of a strictly concave function is zero at some point, then that point is a local maximum. 4. Any local maximum of a concave function is also a global maximum. A "strictly" concave function will have at most one global maximum. Concave function In mathematics, a concave function is the negative of a convex function.
Telecentric lens Telecentric lens A telecentric lens is a compound lens that has its entrance or exit pupil at infinity; in the prior case, this produces an orthographic view of the subject. This means that the chief rays (oblique rays that pass through the center of the aperture stop) are parallel to the optical axis in front of or behind the system, respectively. The simplest way to make a lens telecentric is to put the aperture stop at one of the lens's focal points. An entrance pupil at infinity makes the lens object-space telecentric. Such lenses are used in machine vision systems