Consider the calculator's basic fonction/program generating random
numbers. Each time we press the "enter" button, a number appears
randomly.

The question is:
Would the next number be the same whenever we press the "enter" button
? In other words, if we press the "enter" button in t(0) or in
t(+10s), would it be the same number generated ?

Does it depends on the program ? on the device ?

This issue is important to me, please provide clear and precise explaination.

Yours

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Request for Question Clarification by answerguru-ga on 23 Nov 2005 08:25 PST

Hi michel123-ga,

In general, the generation of a random number can done in one of two ways:

1. The generation is completely random and the user has no control
over the resulting value.

2. The generation is dependent on a "seed" value. Inputting the same
seed value will result in the same number being generated (usually).

The bottom line is that each program/device could have it's own
implementation in generating random numbers, but most fall into one of
the categories above.

Let me know if this information is sufficient to post as an answer.

Thanks,
answerguru-ga

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Clarification of Question by michel123-ga on 23 Nov 2005 09:01 PST

Dear Answerguru, 

Please consider the question for the standard calculator used by high
school students (texas instrument, Ti83).

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Request for Question Clarification by answerguru-ga on 23 Nov 2005 11:49 PST

I couldn't find information regarding the implementation of the random
function on this particular device, however, in general you should
expect any random() call to generate a different value unless you are
providing a seed value.

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Request for Question Clarification by pafalafa-ga on 23 Nov 2005 14:11 PST

Here is some actual source code used for random number generation:


http://www.saliu.com/random-numbers.html


As I understand things, calculators often use the internal clock as a
seed source.  If this is the case, I would fully expect the generation
to be sensitive to the starting time, so that at t=0 and [t=0 +a
microsecond], you'll get two different numbers generated.


What do you think?


pafalafa-ga

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Clarification of Question by michel123-ga on 23 Nov 2005 17:15 PST

Oops... please look at the clarification on "Comments".

It is probably something described here
http://www.mathcom.com/corpdir/techinfo.mdir/scifaq/q210.html
and does not depend on the time taken to press the button.

And this page tells you how to set the seed for the PRNG so that you
can reproduce the pseudo-random sequence.
http://www.central.edu/homepages/lintont/classes/fall00/introstat/srs/srs.html

Thanks to everyone. 

This question was acually asked to share some interpretation of a
personal experience, concerning relation between neuroscience and
quantom physics.

I used to leave close to a 8 or 9 years old child, and initiated him
to some casino games. Since I didn't have any roulette table, I just
generated a random number between 0 and 36 with my calculator (ti83).
The point was naturally to "guess" the number before the program was
executed. One day, when this kid appeared particulary self-confident
(but not over-confident), and after encouraging him to concentrate
deeper, what a nice observation to see him "guessing" 15 correct
numbers, right one after the other one (I stoppped to play after the
15th number).
Mathematically, even if we use to play few days a week during several
months, this event is too low in probability to be a pure coincidence
(1 chance on 37^15).
Note that the result didn't necessarely depend on the person pressing
the button, since in purpose, I was asking few different people to do
it.

True story. Hope you share the importancy of this $2 question.