Lagrange multiplier method
The Lagrange multiplier method is used when one needs to find the extreme or stationary points of a function on a set which is a subset of the domain.
Method
Suppose that and () are differentiable functions that map , and we want to solve
By a calculus theorem, if the constaints are independent, the gradient of , , must satisfy the following equation at the stationary points:
The constraints are said to be independent iff all the gradients of each constraint are linearly independent, that is:
is a set of linearly independent vectors on all points where the constraints are verified.
Note that this is equivalent to finding the stationary points of:
for in the domain and the Lagrange multipliers without restrictions.
After finding those points, one applies the constraints to get the actual stationary points subject to the constraints.
Title | Lagrange multiplier method |
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Canonical name | LagrangeMultiplierMethod |
Date of creation | 2013-03-22 12:25:10 |
Last modified on | 2013-03-22 12:25:10 |
Owner | cvalente (11260) |
Last modified by | cvalente (11260) |
Numerical id | 10 |
Author | cvalente (11260) |
Entry type | Definition |
Classification | msc 49K30 |
Related topic | ExampleOfCalculusOfVariations |
Related topic | IsoperimetricProblem |
Defines | Lagrange multiplier |