Thank-you Berend. This approach does work. Now I need to constrain the problem so that sum(d.NR) is positive for each fleet. I tried this but with no luck:
*nfleets<-2 nareas<-2 M<-1 M<-array(M,dim=c(nfleets,nareas)) N<-1000 cost<-c(40,40) cost<-array(cost,dim=c(nfleets,nareas)) Price<-2 Price<-array(Price,dim=c(nfleets,nareas)) q<-array(0.1,dim=c(nfleets,nareas)) f<-1 f<-array(f,dim=c(nfleets,nareas)) init.eff<-rbind(c(3,3),c(3,3),c(2,2)) #init.eff<-array(3,3,3,3,2,2,dim=c(nfleets,nareas)) OF<-array(c(q*f), dim=c(nfleets, nareas)) Catch<-array(0,dim=c(nfleets, nareas)) f <- array(f, dim=c(nfleets, nareas)) F <- q*f Z <- M+sum(F) S <- exp(-Z) Catch<- N*F/Z*(1-S) Tot.Catch <- sum(Catch) obj<-function(f){ NR<-array(0,dim=c(nfleets,nareas)) NR<-Price*Catch - f*cost d.NR<-array(0,dim=c(nfleets,nareas)) f <- apply(f, 1, sum) d.NR<- N*q/Z*(1-S-F/Z+F/Z*S+F*S)*Price - cost return(sum(d.NR*d.NR)) } init.eff <- init.eff - 1 B <- rbind(c(1,0,1,0,0,0),c(0,1,0,1,0,0),c(0,0,0,0,-sum(N*q/Z*(1-S-F/Z+F/Z*S+F*S)*Price - cost),0),c(0,0,0,0,0,-sum(N*q/Z*(1-S-F/Z+F/Z*S+F*S)*Price - cost))) constropt.eff<-constrOptim(as.vector(init.eff),obj, NULL ,ui=-B, ci=-c(14,14,0,0), method="Nelder-Mead") constropt.eff* Is it possible to constrain my problem in this way? -- View this message in context: http://r.789695.n4.nabble.com/constrained-optimization-help-please-tp4648176p4648526.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.