theta <- .5
iter=2
hattheta=c()
while ((hattheta[iter]-hattheta[iter-1])^2>10^(-2)){
        hattheta[1]<-theta
        hattheta[iter]=(159*hattheta[iter-1]+68)/(197*hattheta[iter-1]+144)
        print(hattheta)
        iter=iter+1

}

显示错误
Error in while ((hattheta[iter] - hattheta[iter - 1])^2 > 10^(-2)) { :
  参数长度为零

迭代公式为：

\[]\theta^{t+1}=\frac{159\theta^{t}+68}{197\theta^{t}+144}\]