Levenberg-Marquardt is a popular alternative to the Gauss-Newton method of finding the minimum of a function that is a sum of squares of nonlinear functions,
Let the Jacobian of be denoted
, then the Levenberg-Marquardt method searches in the
direction given by the solution
to the equations
where
are nonnegative scalars and
is the identity matrix.
The method has the nice property that, for some scalar
related to
, the vector
is the solution of the constrained subproblem of minimizing
subject to
(Gill et al. 1981, p. 136).
The method is used by the command FindMinimum[f, x,
x0
]
when given the Method -> LevenbergMarquardt option.