Calculus Optimization Methods

A key application of calculus is in optimization: finding maximum and minimum values of a function, and which points realize these extrema.

Context edit

Formally, the field of mathematical optimization is called mathematical programming, and calculus methods of optimization are basic forms of nonlinear programming. We will primarily discuss finite-dimensional optimization, illustrating with functions in 1 or 2 variables, and algebraically discussing n variables. We will also indicate some extensions to infinite-dimensional optimization, such as calculus of variations, which is a primary application of these methods in physics.

Techniques edit

Basic techniques include the first and second derivative test, and their higher-dimensional generalizations.

A more advanced technique is Lagrange multipliers, and generalizations as Karush–Kuhn–Tucker conditions and Lagrange multipliers on Banach spaces.

Applications edit

Optimization, particularly via Lagrange multipliers, is particularly used in the following fields:

Further, several areas of mathematics can be understood as generalizations of these methods, notably Morse theory and calculus of variations.

Terminology edit

  • Input points, output values
  • Maxima, minima, extrema, optima
  • Stationary point, critical point; stationary value, critical value
  • Objective function
  • Constraints – equality and inequality
    • Especially sublevel sets
    • Feasible region, whose points are candidate solutions

Statement edit

This tutorial presents an introduction to optimization problems that involve finding a maximum or a minimum value of an objective function   subject to a constraint of the form  .

Maximum and minimum edit

Finding optimum values of the function   without a constraint is a well known problem dealt with in calculus courses. One would normally use the gradient to find stationary points. Then check all stationary and boundary points to find optimum values.

Example edit


  has one stationary point at (0,0).

The Hessian edit

A common method of determining whether or not a function has an extreme value at a stationary point is to evaluate the hessian of the function at that point. where the hessian is defined as


Second derivative test edit

The Second derivative test determines the optimality of stationary point   according to the following rules [2]:

  • If   at point x then   has a local minimum at x
  • If   at point x then   has a local maximum at x
  • If   has negative and positive eigenvalues then x is a saddle point
  • Otherwise the test is inconclusive

In the above example.


Therefore   has a minimum at (0,0).

Sections edit

References edit

[1] T.K. Moon and W.C. Stirling. Mathematical Methods and Algorithms for Signal Processing. Prentice Hall. 2000.