[R] How to write the log function in R

[Ben Bolker]

toh <tohbin <at> yahoo.com> writes:

> 
> 
> Hi,
> 
> I need help to write the following log-likelihood function in R:
> log(L) = sum [(y_k - y_k-1).log(m(t_k) - m(t_k-1)) - (m(t_k) - m(t_k-1)) -
> log((y_k -y_k-1)!)]
> 
> I need to write this log-likelihood function in order to find the parameters
> by MLE method. 
> 

   if you have a vector y_k then diff(y_k) should give you a vector
corresponding to (y_k - y_k-1)  [I assume you mean y_{k-1} rather
than {y_k}-1 above!]

  log(x!) is lfactorial(x) in R

  sum() works as expected

  the rest should be pretty easy ...

  Ben Bolker