General-purpose optimization using heuristic algorithms
Arguments
- par
A numeric vector or list. The length of the par argument defines the number of parameters to be estimated (i.e. the dimension of the problem).
- fn
The function to be minimized.
- gr
Function to compute the gradient of
fn
. Ignored by most methods, added for consistency with other optimization functions.- ...
Additional parameters to be passed to
fn
.- method
The optimization method to be used. The default method is the AHR-ES (Adaptative Hierarchical Recombination Evolutionary Strategy, Oliveros-Ramos & Shin, 2016). See details for the methods available.
- lower
Lower threshold value(s) for parameters. One value or a vector of the same length as par. If one value is provided, it is used for all parameters.
NA
means-Inf
. By default-Inf
is used (unconstrained).- upper
Upper threshold value(s) for parameters. One value or a vector of the same length as par. If one value is provided, it is used for all parameters.
NA
meansInf
. By defaultInf
is used (unconstrained).- active
Boolean vector of the same length as par, indicating if the parameter is used in the optimization (TRUE) or hold at a fixed value (FALSE).
- control
Parameter for the control of the algorithm itself, see details.
- hessian
Logical. Should a numerically differentiated Hessian matrix be returned? Currently not implemented.
- parallel
Logical. Use parallel computation numerical of gradient?
Value
A list with components:
- par
The best set of parameters found.
- value
The value of fn corresponding to par.
- counts
A two-element integer vector giving the number of calls to fn and gr respectively. This excludes those calls needed to compute the Hessian, if requested, and any calls to fn to compute a finite-difference approximation to the gradient.
- convergence
An integer code. 0 indicates successful completion.
- message
A character string giving any additional information returned by the optimizer, or NULL.
- hessian
Only if argument hessian is true. A symmetric matrix giving an estimate of the Hessian at the solution found. Note that this is the Hessian of the unconstrained problem even if the box constraints are active.