警告信息: step halving factor reduced below minimum in PNLS step

[imnotathome]

library(forestat)

加载包中 forestData 样例数据

data("forestData")

基于 forestData 数据建立模型，返回一个 forestData 类对象

forestData <- class.plot(forestData, model = "Richards",

•                      interval = 5, number = 5,
  

•                      H_start=c(a=20,b=0.05,c=1.0))
  

警告信息:
1: In nlme.formula(BA ~ a * (1 - exp(-b * (S/1000)^c * AGE))^d, data = data, :
step halving factor reduced below minimum in PNLS step
2: In nlme.formula(BA ~ a * (1 - exp(-b * (S/1000)^c * AGE))^d, data = data, :
step halving factor reduced below minimum in PNLS step
3: In nlme.formula(Bio ~ a * (1 - exp(-b * (S/1000)^c * AGE))^d, data = data, :
step halving factor reduced below minimum in PNLS step
4: In nlme.formula(Bio ~ a * (1 - exp(-b * (S/1000)^c * AGE))^d, data = data, :
step halving factor reduced below minimum in PNLS step