#国外某论坛上的解决方案，达到循环限制仍未收敛，用lmeControl修改最大循环限制(具体见？lmeControl)，代码如下：
#Try ?lmeControl
#Setting the maxIter, msMaxIter, niterEM, and/or msMaxEval arguments to higher values than the default #may fix this. #Capture the output from lmeControl to an object and then pass that object to the control #argument of lme.
ctl <- lmeControl (msMaxIter=100)
m0 <- lme(height~age + I(age^2) + I(age^3),Loblolly,
          random=list(Seed=~age+I(age^2)+I(age^3)),
          correlation=corCAR1(form=~age|Seed), control=ctl)
m0
plot (m0)

nlminb problem, convergence error code = 1
  message = iteration limit reached without convergence (9)
楼主，我也遇到同样问题，你的解决了吗

如果模型无法收敛，可改变control设置。
收敛问题可以通过更改模型迭代限制(maxIter)或更改模型优化器(opt)来解决。例如`control = list (maxIter = 100, opt = "optim")`将把最大迭代次数改为100，优化器改为optim