Nonlnear Models - GLS

### Indometh

ols<-nls(conc~SSbiexp(time,b1,b2,b3,b4),
              data=Indometh[Indometh$Subject==1,])
beta<-coef(ols)

for(i in 1:10){
  oldbeta<-beta
  out<-nls(conc~SSbiexp(time,b1,b2,b3,b4),
             data=Indometh[Indometh$Subject==1,],
             weights=1/SSbiexp(time,beta[1],beta[2],beta[3],beta[4])^2)
  beta<-coef(out)              
}

BETA<-matrix(rep(0,6*4),6)
for(i in 1:6){
  BETA[i,]<-coef(nls(conc~SSbiexp(time,b1,b2,b3,b4),
            data=Indometh[Indometh$Subject==i,]))
}
colnames(BETA)<-c('b1','b2','b3','b4')


### Theoph
coplot(conc~Time | Subject, data=Theoph)
nls(conc~SSfol(Dose,Time,lKe,lKa,lCl),data=Theoph)
ols<-nls(conc~SSfol(Dose,Time,lKe,lKa,lCl),
              data=Theoph[Theoph$Subject==1,])
beta<-coef(ols)

BETA<-matrix(rep(0,12*3),12)
for(i in 1:max(as.numeric(Theoph$Subject)))
  BETA[i,]<-coef(nls(conc~SSfol(Dose,Time,b1,b2,b3),
                 data=Theoph[Theoph$Subject==i,]))