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
