[R] for help about MLE in R

[Edward Sun]

Dear Sir,

I am using R to estimate two parameters in Normal distribution. I generated 
100 normal distributed numbers, on which to estimate the parameter. The 
syntax is:

>fn<-function(x)-50*log((y)^2)+50*log(2*pi)-(1/2*(z^2))*(sum((x-y)^2))
>out<-nlm(fn, x, hessian=TRUE)

but it does not work. Could you please help me to compose the syntax for the 
purpose that find maximum likelihood estimates of the generated random 
numbers by direct maximization of the likelihood function?

Thanks a lot.

Best regards
Edward Sun