fdat=read.table(file="lll.txt",header = T)
YM=fdat$Y/fdat$M
LM=fdat$L/fdat$M  
KM=fdat$K/fdat$M  
summary(YM)
summary(LM)
summary(KM)
nl.f=nls(YM~A*(LM^a)*(KM^(1-a)),start=list(A=0.5,a=1),trace=T)
summary(nl.f)

library("maxLik")
loglik=function(para){
  N=length(YM)
  e=YM-para[1]*LM^para[2]*KM^(1-para[2])
  ll=-0.5*N*(1+log(2*pi)-log(N))-0.5*N*log(sum(e^2))
  return(ll)
}
res=maxLik(loglik,start=c(0.5,1),method="NR")
summary(res)

plot(YM~LM)
lines(LM, fitted(nl.f))
plot(YM~KM)
lines(KM, fitted(nl.f))
Rsq<-1-sum(resid(nl.f)^2)/(sum((YM-mean(YM))^2))
Rsq

adjRsq<-1-(length(YM)-1)/(length(YM)-2)*(1-Rsq)
adjRsq

anova(nl.f,lm.f)    ！！！object 'lm.f' not found

Q = -2*(logLik(nl.f)-logLik(lm.f))
df.Q=df.residual (nl.f)-df.residual(lm.f)
1-pchisq(Q,df.Q)