From Wikipedia, the free encyclopedia.
In chemistry, a critical point is the conditions (temperature, pressure) at which the fluid state of the matter ceases to exist.
In physics, it often also means the point of a second order phase transition.
In mathematics, a critical point (or critical number) is a point on the graph of a function where the derivative is either infinite, undefined, or equal to zero. The latter kind is a stationary point.
In higher dimensions, and for functions of several variables, this concept becomes a point where the rank of the derivative (Jacobian matrix) drops (see submersion).
