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Re: [PATCH] Makes sort create random order


From: Frederik Eaton
Subject: Re: [PATCH] Makes sort create random order
Date: Sun, 30 Jan 2005 15:01:12 -0800
User-agent: Mutt/1.5.6+20040907i

> > seq feature for other things as well, I think, provided it was well
> > implemented - e.g. 'jot' seems to seed it's RNG from epoch seconds,
> > which is no good, microseconds would be better. The disadvantage is
> 
> Yes, but there's two points here:
> 1) There's generally a way to the user to specify a seed. Tipically this 
>    value is specified in the last argument (step value in nornal mode).

Would we have to keep BSD syntax? I think that's confusing - since
specifying a seed would probably be rarely done, I think it should be
a long option instead. (And I'm just saying that the default should be
that if you run it several times in a row, each time it will give
different results, which isn't the case if you use seconds. I guess
perl seeds from /dev/urandom if available, and if not then some
combination of time, $$, and something with memory allocation - but
these are unimportant details)

> 2) Today's implementations are using other randomizations than a simple 
>    s?rand(3) -- take for example the OpenBSD's implementation (uses ARC4), 
>    though this implemantion doesn't specify user-specified seed.

I'm sure something better than the libc rand implementations wouldn't
be objectionable, as long as it is actually better.

> I'd sum the good decisions of these implementations up in seq this way
> 
> 1) Generate 4 random values (ranging from 1 to 4):
> $ seq -r 4
> 
> 2) Generate 4 random values (ranging from 4 to 7):
> $ seq -r 4 7
> 
> 3) Generate 4 random values (ranging from 4 to 7, seed 3):
> $ seq -r 4 3 7
> 
> 4) Generate an endless number of random values (useful with head):
> $ seq -r
> 
> Does anyone have suggestions on this?

Hmm, I don't like the syntax. As I said, having the seed where
'increment' should be is confusing. And how do I generate 8 random
values from 1 to 10000? How do I generate an endless number of random
values from 4 to 7?

Frederik

-- 
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Frederik Eaton                         http://ofb.net/~frederik/




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