[R-sig-ME] lower and upper bounds for optimizer="nloptwrap"

[Andras Farkas]

Hello,

wonder if I could get some help on how to specify lower and upper bounds for optimizer="nloptwrap". To date my approach looks like:


lmercontrollist<-lmerControl(optimizer = "nloptwrap",
                             restart_edge = TRUE,
                             boundary.tol = 1e-5,
                             calc.derivs = TRUE,
                             use.last.params = FALSE,
                             sparseX = FALSE,
                             standardize.X = FALSE,
                             ## input checking options
                             check.nobs.vs.rankZ = "ignore",
                             check.nobs.vs.nlev = "stop",
                             check.nlev.gtreq.5 = "ignore",
                             check.nlev.gtr.1 = "stop",
                             check.nobs.vs.nRE= "stop",
                             check.rankX = c("message+drop.cols", "silent.drop.cols", "warn+drop.cols",
                                             "stop.deficient", "ignore"),
                             check.scaleX = c("warning","stop","silent.rescale",
                                              "message+rescale","warn+rescale","ignore"),
                             check.formula.LHS = "stop",
                             ## convergence checking options
                             check.conv.grad     = .makeCC("warning", tol = 2e-3, relTol = NULL),
                             check.conv.singular = .makeCC(action = "message", tol = formals(isSingular)$tol),
                             check.conv.hess     = .makeCC(action = "warning", tol = 1e-6),
                             ## optimizer args
                             optCtrl = list(maxeval=100,lower = rep.int(0, 21),upper = rep.int(5, 21)),
                             mod.type = "lmer")

let us ignore model appropriateness here and just focus on the constraints: 

m1 <- lmer(Reaction ~ Days + Subject+ (1|Days),data=sleepstudy,verbose=1,control =lmercontrollist)
summary(m1)


 as you will see the fixed effect values are negative. I also tried lb and ub instead of lower and upper based on nloptr function, but also did not help. Besides, just to be sure I understand correctly, the length of the lower/upper bounds must be the same as the length of fixed and random effect, correct? here I set to 21 based on output but am not exactly sure if the residual has to be included in the count or not...

much appreciate your help,

Andras