Used to find the Extremum of
subject to the constraint
where and are functions with continuous first Partial Derivatives on the Open
Set containing the curve
at any point on the curve
(where is the Gradient). For an Extremum to exist,
See also Kuhn-Tucker Theorem
Arfken, G. ``Lagrange Multipliers.'' §17.6 in Mathematical Methods for Physicists, 3rd ed.
Orlando, FL: Academic Press, pp. 945-950, 1985.