stats4中似乎有个mle的类,这是文档中的一个例子，需要先加s4包
<br />
## Avoid printing to unwarranted accuracy<br />
od <- options(digits = 5)<br />
x <- 0:10<br />
y <- c(26, 17, 13, 12, 20, 5, 9, 8, 5, 4, 8)</p>
<p>## Easy one-dimensional MLE:<br />
nLL <- function(lambda) -sum(stats::dpois(y, lambda, log=TRUE))<br />
fit0 <- mle(nLL, start = list(lambda = 5), nobs = NROW(y))<br />
</p>
