TOPICS
Search

Saddle Point


A point of a function or surface which is a stationary point but not an extremum. An example of a one-dimensional function with a saddle point is f(x)=x^3, which has

f^'(x)=3x^2
(1)
f^('')(x)=6x
(2)
f^(''')(x)=6.
(3)

This function has a saddle point at x_0=0 by the extremum test since f^('')(x_0)=0 and f^(''')(x_0)=6!=0.

Surfaces can also have saddle points, which the second derivative test can sometimes be used to identify. Examples of surfaces with a saddle point include the handkerchief surface and monkey saddle.


See also

Game Saddle Point, Hyperbolic Fixed Point, Second Derivative Test

Explore with Wolfram|Alpha

Cite this as:

Weisstein, Eric W. "Saddle Point." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/SaddlePoint.html

Subject classifications