Thanks to everybody for all the suggestions and help. I shall try out the 32/64 bit experiment in my next class.
Best. Arnab. On Fri, Feb 7, 2020 at 6:28 AM bill lam <[email protected]> wrote: > Android with armv7 cpu are 32 bit, with armv8 cpu are 64 bit. They give > different results for RNG. > > 32 vs 64 bit can be checked by the global noun IF64 > > > > On Thu, Feb 6, 2020, 9:18 PM 'Rob Hodgkinson' via Programming < > [email protected]> wrote: > > > Hi Arnab, further to Pascal’s note I would suggest the following > approach: > > Set the random seed for the RNG to a value you desire (see the > > Foreign Conjunction 9!:1 ) > > Then call ?n as you wish to produce a sequence as many times as > > you wish > > > > Repeat sequence above to reproduce from a preset seed, for example: > > > > First run: > > 9!:1 ] 3581 NB. Set RNG Seed to 3581 > > > > ?8 > > 2 > > ?100 100 100 > > 10 28 71 > > ?8 > > 5 > > > > Now repeat: > > 9!:1 ] 3581 NB. Reset RNG Seed to 3581 again to reproduce > above > > > > ?8 > > 2 > > ?100 100 100 > > 10 28 71 > > ?8 > > 5 > > > > I believe (untested) this approach should produce the same results across > > your students devices. > > > > Best, Rob > > > > > On 7 Feb 2020, at 12:14 am, 'Pascal Jasmin' via Programming < > > [email protected]> wrote: > > > > > > The initial seed is the same each time you start J. > > > ?. differs on 32 and 64 bit systems, with default generator. > > > On Thursday, February 6, 2020, 07:21:31 a.m. EST, Arnab Chakraborty > < > > [email protected]> wrote: > > > > > > Dear all, > > > > > > For my class of about 30 students armed with JAndroid 901, I had > planned > > to > > > use ?. to generate a random matrix which should be same for everybody. > To > > > start with, I asked everybody to try > > > > > > ?. 100 > > > > > > Some got 46, others got 93. No other values. Next, someone noticed that > > if > > > they repeatedly type > > > > > > ? 100 > > > > > > then many are getting the SAME sequence of "random" numbers. Hence my > > > question: > > > > > > 1) Is there a way to produce predictable "random numbers" across > > different > > > machines (all running Jandroid 901_*, where the *'s may differ)? > > > > > > 2) Is there some way to get the initial seed from, say, the system > time > > in > > > millisecond (or something like that)? > > > > > > Thanks a lot. > > > > > > Arnab. > > > > > > PS: BTW, my students are loving J! > > > ---------------------------------------------------------------------- > > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > > > ---------------------------------------------------------------------- > > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
