chase321 wrote: > I have been using Gnumeric for some time in the statistics classes I teach. > This past semester, I did my first online section, and had them submit labs > using Gnumeric. For one lab, I had them use the "randbetween" function to > generate random numbers. 9 of the 17 labs I received had identical sets of > random numbers. This makes me more than a little suspicious, but I have > also seen students get the same sequence of numbers in the classroom. I > know enough about pseudorandom number generators to know that if two people > start at the same point in the sequence, they're going to get the same set > of numbers. So I have two questions. > 1) How is the pseudorandom number generator initialized (seeded)? > 2) Is there any way to seed it manually? I can find no function for this > mentioned in the manual. > > Thanks for any help.
Hi Chase, Looking at the code in plugins/fn-random/functions.c and src/mathfunc.c it appears rand_01 is the relevant function. By setting the environment variable GNUMERIC_PRNG_SEED (on unix with a bourne compatible shell with something like $ export GNUMERIC_PRNG_SEED=some_random_string ) will cause rand_01 to use a pseudo random number generator using the specified seed. Otherwise it should get its random numbers from /dev/urandom My understanding of this is that if GNUMERIC_PRNG_SEED is set then each time you open a sheet containing randbetween you will get the same value, whereas if it isn't then you won't. Are you using windows by any chance? Kind regards, Hal _______________________________________________ gnumeric-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/gnumeric-list
