Rdistance (version 2.1.3)

RdistanceControls: Control parameters for Rdistance optimization.

Description

Returns a list of optimization controls used in Rdistance and provides a way to change them if needed.

Usage

RdistanceControls(optimizer = "nlminb", evalMax = 2000,
  maxIters = 1000, likeTol = 1e-08, coefTol = 1.5e-08,
  hessEps = 1e-08)

Arguments

optimizer

A string specifying the optimizer to use. Results vary between optimizers, so switching algorithms sometimes makes a poorly behaved distance function converge. The valid values are "optim" which uses optim::optim, and "nlminb" which uses stats:nlminb. The authors have had better luck with "nlminb" than "optim" and "nlminb" runs noticeably faster. Problems with solutions near parameter boundaries may require use of "optim".

evalMax

The maximum number of objective function evaluations allowed.

maxIters

The maximum number of optimization iterations allowed.

likeTol

The maximum change in the likelihood (the objective) between iterations that is tolerated during optimization. If the likelihood changes by less than this amount, optimization stops and a solution is declared.

coefTol

The maximum change in the model coefficients between iterations that is tolerated during optimization. If the sum of squared coefficient differences changes by less than this amount between iterations, optimization stops and a solution is declared.

hessEps

A vector of parameter distances used during computation of numeric second derivatives. Should have length 1 or the number of parameters in the model. See function secondDeriv.

Value

A list containing named components for each of the controls. This list has the same components as this function has input parameters.

Examples

# NOT RUN {
# increase number of iterations
RdistanceControls(maxIters=2000)

# change optimizer and decrease tolerance
RdistanceControls(optimizer="optim", likeTol=1e-6) 

# }