Hi All,
That's good news. Then we could also use the random number support from the
MS Crypto API. I believe that they split it off so that you no longer have to
drag in the whole API too.
I used to see people build roll-your-own web session cookies from PRNGs and
they were 100% failures. An e-commerce site I tested one, we worked out away
to guess someone else's session cookie in about 5 minutes.
This isn't needed for simulations but it's made me distrustful.
David
>________________________________
> From: Kostas Oikonomou <k...@research.att.com>
>To: Phillip <p...@firefly.nlm.nih.gov>
>Cc: Jafar Al-Gharaibeh <to.ja...@gmail.com>; David Gamey
><david.ga...@rogers.com>; UniconGroup <unicon-group@lists.sourceforge.net>
>Sent: Friday, February 3, 2012 11:47:04 AM
>Subject: Re: [Unicon-group] &random behaviour and documentation.
>
>With the forthcoming improved C interface (heavy hint to Clint here) you
>should also be able to use the random routines in the GSL, which may solve
>some of these problems.
>I use their Mersenne twister in some of my code.
>
>Kostas
>
>Sent from my iPhone
>
>On Feb 3, 2012, at 10:04 AM, Phillip <p...@firefly.nlm.nih.gov> wrote:
>
>> Yes, we finally(!) about a year ago set the normal random by default not
>> to always produce the same number -- this is true in the UNIX versions, I
>> believe, but I don't know if it reached the windows side. My argument was
>> that having the default always produce the same number was only useful in
>> some testing situations but never in any production program. The problem
>> here -- if you accept my random philosophy -- is that the results are too
>> clustered.
>>
>> I had a physicist friend who was about ready to present a paper with
>> startling results (different operation system than available now and not
>> Unicon) only to find that the random number generation was giving the same
>> value each time. He had to withdraw his paper. From this experience, I've
>> never trusted my off-the-top-of-my-head, post-midnight, kludges to produce
>> a random seed adequately for a given task, assuming that I even remembered
>> to randomize the randomizer.
>>
>> --Phillip
>>
>>
>> On Thu, 2 Feb 2012, Jafar
>> Al-Gharaibeh wrote:
>>
>>> Hi David,
>>>
>>> I believe &random is the seed and not to be confused with the random
>>> sequence you would get if you use the "?" operator. &random probably gets
>>> its initial value using the system clock with some simple math. That is why
>>> you have numbers (seeds) that are all clustered together since probably you
>>> ran the program several times around the same clock. If you want the same
>>> sequence to be repeated, set &random at program start up to a specific
>>> value, zero for example, but if you want random numbers you can do
>>> something like
>>>
>>> ?x # where x is 10^6 for example to get numbers in the range of [0 :
>>> 10^6-1 ]
>>> # (have to double check if I got the boundaries right)
>>>
>>> In any case, the Unicon book seems to be inconsistent about whether the
>>> value of &random is "randomly" set at start up or not. I believe it is.
>>>
>>> Jafar
>>>
>>>
>>>
>>> On Thu, Feb 2, 2012 at 3:59 PM, David Gamey <david.ga...@rogers.com> wrote:
>>>
>>>> Hi Folks,
>>>>
>>>> I know the built-in PRNG is a bit quirky and as I understand it Unicon
>>>> departed from Icon by randomizing it initially (although UB3/Sesrit
>>>> contradicts this).
>>>>
>>>> If I run this several times on Win7/x64 UniconV12:
>>>>
>>>> procedure main();write("&random=",&random);end
>>>>
>>>> I get only minor variations:
>>>>
>>>> &random=20122651
>>>> &random=20122851
>>>> &random=20123251
>>>> &random=20123351
>>>> &random=20123451
>>>> &random=20122961
>>>> &random=20123161
>>>> &random=20123261
>>>> &random=20123361
>>>> &random=20123461
>>>>
>>>> Does anyone have any idea what is supposed to happen?
>>>>
>>>> This doesn't help much for testing (fixed &random) or for simulation
>>>> (random &random)
>>>>
>>>> David
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
>>> --
>>> "Let there be no compulsion in religion: Truth stands out clear from error"
>>> [The Holy Qur'an 2:256]
>>>
>>> "Injustice anywhere is a threat to justice everywhere" Dr. King
>>>
>>
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