[R] lapply() reccursively

[Kaveh Vakili]

Hi all,

I was wondering whether it is possible to use the lapply() function
to alter the value of the input, something in the spirit of :

a1<-runif(100)
a2<-function(i){
a1[i]<-a1[i-1]*a1[i];a1[i]
}
a3<-lapply(2:100,a2)

Something akin to a for() loop, but using the lapply() infrastructure.
I haven't been able to get rapply() to do this.

The reason is that the "real" a2 function is a difficult function that only needs to be evaluated if the value of a1[i-1] meets some criteria.

Thanks in advance,