(j3.2006) RANDOM_INIT question

[Bill Long]

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. 

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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