R help - Jun 2005 - random number generator: same seed used in different sessions

I did several simulation sessions and the result turned out to be a
surprise. After some investigation, I found that different R sessions
of the program used the same seed. Simply, in R210, if I start R and
type rnorm(1), I always get the same random number. This is
contradictary to what is in the R document

 Initially, there is no seed;  a new one is created from the
     current time when one is required.  Hence, different sessions will
     give different simulation results, by default.

I just installed the development version R220. Different sessions of R
do use different seeds as expected.





Jason Liao, http://www.geocities.com/jg_liao
Dept. of Biostatistics, http://www2.umdnj.edu/bmtrxweb
University of Medicine and Dentistry of New Jersey
683 Hoes Lane West, Piscataway? NJ 08854
phone 732-235-5429, School of Public Health office
phone 732-235-9824, Cancer Institute of New Jersey office

On Wed, 15 Jun 2005, Jason Liao wrote:
> I did several simulation sessions and the result turned out to be a
> surprise. After some investigation, I found that different R sessions
> of the program used the same seed. Simply, in R210, if I start R and
> type rnorm(1), I always get the same random number. This is
> contradictary to what is in the R document
>
> Initially, there is no seed;  a new one is created from the
>     current time when one is required.  Hence, different sessions will
>     give different simulation results, by default.
That is not a contradiction!  Did you ensure that this really was 
`initially', so there is no saved workspace, no .Rprofile etc?
See if starting with R --vanilla makes a difference.
> I just installed the development version R220. Different sessions of R
> do use different seeds as expected.
There are no R versions R210 or R220: please do read the posting guide
as we ask:
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595