我要用极大似然方法对收入的分布进行估计，假定服从gamma分布

    di=read.table("di.txt",header=TRUE)

    attach(di)   #di中有变量dio2和di03

    library(stats4)

    ll=function(lambda,alfa){n=500

                                       x=di02

    -n*alfa*log(lambda)+n*log(gamma(alfa))-(alfa-1)*sum(log(x))+lambda*sum(x)}

   est=mle(minuslog=ll,start=list(lambda=2,alfa=1))

  summary(est)

运行后提示大量出错信息：

Error in optim(start, f, method = method, hessian = TRUE, ...) :

  non-finite finite-difference value [1]

In addition: There were 50 or more warnings (use warnings() to see the first 50)

估计结果也不对，麻烦高手给看看问题出在哪，谢谢。

[此贴子已经被作者于2009-3-30 13:47:35编辑过]