[R] .Random.seed

[Ann Hess]

I am writing a function for the purposes of a simulation.  Due to memory
problems, the function sometimes crashes.  In order to get around this
problem, I would like to include to be able to save the "last" seed, so I
can pick up with the next run of the simulation after a "crash".  I am
having trouble understanding what is going on with .Random.seed!

For each run of the following function, a random uniform and the current
.Random.seed should be printed:

test<-function(runs,seed){
   .Random.seed<-seed
   for (i in 1:runs) {
print(i)
print(runif(1,0,1))
print(.Random.seed)}
   return(.Random.seed}

Consider the following input/output:
>RNGkind(kind="Marsaglia-Multicarry")
> set.seed(20391)
> seed1<-.Random.seed
> seed1
[1]         401 -1607331462  -462081869
> test(2,seed1)
[1] 1
[1] 0.4188851
[1]         401 -1607331462  -462081869
[1] 2
[1] 0.7713649
[1]         401 -1607331462  -462081869
[1]         401 -1607331462  -462081869
> seed1
[1]         401 -1607331462  -462081869
> test(2,seed1)
[1] 1
[1] 0.7293294
[1]         401 -1607331462  -462081869
[1] 2
[1] 0.8266798
[1]         401 -1607331462  -462081869
[1]         401 -1607331462  -462081869


The output from each call of the function seems to suggest that
.Random.seed is not changing (although different random uniforms are
generated each time).  The second call of the function doesn't match the
first call even though the same "seed" is used.

Can anyone explain what is happening here?  My goal is to save the "last"
seed so that I can use it to generate the next run of a simulation (after
a crash).

Thanks in advance!