(j3.2006) RANDOM_INIT question

[John Reid]

Bill Long wrote:
> OK.  I?ll keep a copy of this email for future use when questions arise.
>
> I do think it would be at least a good idea to link what RANDON_INIT does to RANDOM_NUMBER.  In the description of RANDOM_SEED, we specify "The pseudorandom number generator used by RANDOM_NUMBER?.  We should make the ?used by RANDOM_NUMBER? connection in RANDOM_INIT as well.   That would close the loop to connect RANDOM_INIT to the description of RANDOM_SEED where the requirement of the ?same sequence? is stated.

Agreed.

John.





> Cheers,
> Bill
>
>
> On Sep 21, 2015, at 7:16 PM, Malcolm Cohen <malcolm at nag-j.co.jp> wrote:
>
>> <<<
>>   Since ?repeatable?  can be used to describe whether a generator would
>> generate the same sequence given a particular starting seed,  there is
>> possibility of confusion.
>>>>>>
>>
>> There is no confusion in the standard.
>>
>> The actual words in the standard
>> (a) explicitly specify that this is a pseudo-random number generator, not a
>> (scare quotes) "true random" generator;
>> (b) explicitly specify that a particular seed, (actual quote) "shall result
>> in the same sequence of pseudorandom numbers being generated";
>> (c) explicitly specify that REPEATABLE=.FALSE. merely sets the seed (actual
>> quote) "to a processor-dependent, unpredictably different value on each
>> call".
>>
>> There is no ambiguity here!
>>
>> <<<
>>   A Note to say that there is only one generator, and we don?t mean that
>> usage of ?repeatable?,  might be clarifying.
>>>>>
>>
>> We have Already Fully Specified *Precisely* what the effect of the *Argument
>> Whose Name Is "REPEATABLE"* is.
>>
>> In fact we do not use the word "repeatable" ***ANYWHERE IN THE ENTIRE
>> STANDARD***.  Not even once.  Not here, and not anywhere else either.  The
>> argument name is REPEATABLE, that's it.  And I repeat, the semantics are
>> Fully Specified.
>>
>> Such a note, following the text which actually Specifies The Semantics
>> Normatively, would not only be completely unnecessary but also
>> counter-productive.  One might as well word it as "You might think that you
>> can ignore the semantics we've just specified, because you went into an
>> entire imaginary world based on the spelling of the argument name, but you
>> would be wrong."
>>
>> There is simply No Case To Answer here.
>>
>> Grumpily,
>> --
>> ..............................The Editor.
>>
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>
> Bill Long                                                                       longb at cray.com
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