[R] random number generator: same seed used in different sessions

From: Jason Liao <jg_liao_at_yahoo.com>
Date: Thu 16 Jun 2005 - 02:19:14 EST


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

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