Re: randomize

Re: randomize

[Wolfgang Werners-Lucchini]

> > I know this and I have triggerd this by hand. So there is a lot of
> > time between. I have purged files between every run and I got the
> > same result if I wait 1 second, 1 minute or 1 day.
> 
>   Well, then it probably qualifies as a bug, and, since the .tuc
> file
> has apparently been dismissed as a cause,  you'd have to provide
> more
> precise information if you're interested in having it corrected (or
> do the debugging yourself, of course).
> 
> 	Arthur

I have found a discussion on this thema. See

http://lua-users.org/lists/lua-l/2007-03/msg00564.html

So I have changed the example to

-------------------------------------------------------------
\starttext
\startluacode
math.randomseed(os.time())
_=math.random()
\stopluacode

Encode your Name and Surname as a
\startluacode
local a = {'null-terminated', 'dollar-terminated', 'Pascal'}
context('%s string', a[math.random(1,3)])
\stopluacode
\stoptext
-------------------------------------------------------------

and this is working ok!

Wolfgang
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Re: randomize

[Arthur Reutenauer]

> http://lua-users.org/lists/lua-l/2007-03/msg00564.html

  Interesting, thanks for the research.  So now we know you use a Mac :-)

	Arthur
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Re: randomize

[Wolfgang Schuster]

Am 08.04.10 09:41, schrieb Arthur Reutenauer:
>> http://lua-users.org/lists/lua-l/2007-03/msg00564.html
>>      
> Interesting, thanks for the research.  So now we know you use a Mac :-)
>    
Sure? I think he use windows, take a look at the mail header:

Pegasus Mail for Windows (4.41, DE v4.41 R1)

Wolfgang

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Re: randomize

[Arthur Reutenauer]

> Sure? I think he use windows, take a look at the mail header:
>
> Pegasus Mail for Windows (4.41, DE v4.41 R1)

  Right, I was misled by the thread on the Lua list he pointed to, that
focused on the rand() implementation on Mac OS and other BSD descendants
(I had overseen that it mentioned the same problem also happened on
Windows).  But let's drop the discussion there, lest Anonymous ConTeXt
User starts worrying we're going to track him down, too :-) (I have
contacts at Google on different continents!)

	Arthur
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Re: randomize

[Arthur Reutenauer]

> I know this and I have triggerd this by hand. So there is a lot of 
> time between. I have purged files between every run and I got the 
> same result if I wait 1 second, 1 minute or 1 day.

  Well, then it probably qualifies as a bug, and, since the .tuc file
has apparently been dismissed as a cause,  you'd have to provide more
precise information if you're interested in having it corrected (or do
the debugging yourself, of course).

	Arthur
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Re: randomize

[Wolfgang Werners-Lucchini]

> > Now it works. But WHY?
> 
>   Because that's the way random number generators works.  They're
> not
> random at all, they generate completely predictable number
> sequences
> from a "seed": each time you use the same seed, you get the exact
> same
> sequence.  In your case, you used os.time() as a seed, which is an
> integral number of seconds elapsed since some fixed date, and the
> fact
> you saw the same number ten times simply means your code was ran
> ten
> times within the same second.

I know this and I have triggerd this by hand. So there is a lot of 
time between. I have purged files between every run and I got the 
same result if I wait 1 second, 1 minute or 1 day.

Wolfgang
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Re: randomize

[Arthur Reutenauer]

> Now it works. But WHY?

  Because that's the way random number generators works.  They're not
random at all, they generate completely predictable number sequences
from a "seed": each time you use the same seed, you get the exact same
sequence.  In your case, you used os.time() as a seed, which is an
integral number of seconds elapsed since some fixed date, and the fact
you saw the same number ten times simply means your code was ran ten
times within the same second.

	Arthur
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Re: randomize

[Wolfgang Werners-Lucchini]

> >> Delete the tuc file with 'context --purgeall'.
> >>      
> > This does not work! I get allways the same.
> >    
> Delete
> 
> \startluacode
> math.randomseed(os.time())
> \stopluacode
> 
> in your file.

Now it works. But WHY?

Wolfgang
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Re: randomize

[Wolfgang Werners-Lucchini]

> > I get allways (10 times at least) the same result:
> > -------------------------------------------------------------
> > \starttext
> > \startluacode
> > math.randomseed(os.time())
> > \stopluacode
> >
> > Encode your Name and Surname as a
> > \startluacode
> > local a = {'null-terminated', 'dollar-terminated', 'Pascal'}
> > context('%s string', a[math.random(1,3)])
> > \stopluacode
> > \stoptext
> > -------------------------------------------------------------
> > How can I randomize this?
> 
> Hmm... which version are you using?  I do get a ranom output each
> time.
> Tested with 2009.12.31 and  2010.03.20.

This is LuaTeX, Version beta-0.60.0-2010040521 (rev 3596) 
 \write18 enabled.
(tst-b.tex

ConTeXt  ver: 2010.03.30 18:56 MKIV  fmt: 2010.4.7  int: 
english/english
 
> Since the math seed is set after \starttext, it should overwrite the
> value after reading the tuc file.
> 
> Actually, I consider saving the random number in tuc file to be a 
> misfeature. A random sequence generator should generate a random
> sequence. 
> If I want the same behavior all the time, I can use 
> \setupsystem[random=12345] (which should also set 
> math.randomseed).

I agree with this!
A feature could be to save the last used random value in the tuc, so 
that one can continue with the former used sequenz. But this should 
not be used automatically, too. May be one should than say

\setupsystem[random=last]

Wolfgang

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Re: randomize

[luigi scarso]

On Wed, Apr 7, 2010 at 5:05 AM, Aditya Mahajan <adityam@umich.edu> wrote:
> On Tue, 6 Apr 2010, Wolfgang Werners-Lucchini wrote:
>
>> Hallo,
>>
>> I get allways (10 times at least) the same result:
>> -------------------------------------------------------------
>> \starttext
>> \startluacode
>> math.randomseed(os.time())
>> \stopluacode
>>
>> Encode your Name and Surname as a
>> \startluacode
>> local a = {'null-terminated', 'dollar-terminated', 'Pascal'}
>> context('%s string', a[math.random(1,3)])
>> \stopluacode
>> \stoptext
>> -------------------------------------------------------------
>> How can I randomize this?
>
> Hmm... which version are you using?  I do get a ranom output each time.
> Tested with 2009.12.31 and  2010.03.20.
>
> Since the math seed is set after \starttext, it should overwrite the value
> after reading the tuc file.

Same here:

# for j in `seq 1 100`; do context test.tex &> /dev/null; pdftotext
test.pdf  -|grep Encode; done >> out

# nl out |tail -1
   100	Encode your Name and Surname as a null-terminated string

# grep 'Encode your Name and Surname as a Pascal string' out |nl|tail -1
    33	Encode your Name and Surname as a Pascal string

# grep 'Encode your Name and Surname as a dollar-terminated string'
out |nl|tail -1
    35	Encode your Name and Surname as a dollar-terminated string

# grep 'Encode your Name and Surname as a null-terminated string' out
|nl|tail -1
    32	Encode your Name and Surname as a null-terminated string

which is pretty good for only 100 samples

-- 
luigi
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Re: randomize

[Hans Hagen]

On 7-4-2010 5:05, Aditya Mahajan wrote:
> On Tue, 6 Apr 2010, Wolfgang Werners-Lucchini wrote:
>
>> Hallo,
>>
>> I get allways (10 times at least) the same result:
>> -------------------------------------------------------------
>> \starttext
>> \startluacode
>> math.randomseed(os.time())
>> \stopluacode
>>
>> Encode your Name and Surname as a
>> \startluacode
>> local a = {'null-terminated', 'dollar-terminated', 'Pascal'}
>> context('%s string', a[math.random(1,3)])
>> \stopluacode
>> \stoptext
>> -------------------------------------------------------------
>> How can I randomize this?
>
> Hmm... which version are you using? I do get a ranom output each time.
> Tested with 2009.12.31 and 2010.03.20.
>
> Since the math seed is set after \starttext, it should overwrite the
> value after reading the tuc file.
>
> Actually, I consider saving the random number in tuc file to be a
> misfeature. A random sequence generator should generate a random
> sequence. If I want the same behavior all the time, I can use
> \setupsystem[random=12345] (which should also set math.randomseed).

the reason is that otherwise (esp if the randomization produced 
different input, graphic sizes, etc) you can get oscilation and endless 
runs due to never quite right multipass data which is pretty hard to debug

Hans

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Re: randomize

[Wolfgang Schuster]

Am 07.04.10 01:10, schrieb Wolfgang Werners-Lucchini:
>> Delete the tuc file with 'context --purgeall'.
>>      
> This does not work! I get allways the same.
>    
Delete

\startluacode
math.randomseed(os.time())
\stopluacode

in your file.

Wolfgang

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Re: randomize

[Aditya Mahajan]

On Tue, 6 Apr 2010, Wolfgang Werners-Lucchini wrote:

> Hallo,
>
> I get allways (10 times at least) the same result:
> -------------------------------------------------------------
> \starttext
> \startluacode
> math.randomseed(os.time())
> \stopluacode
>
> Encode your Name and Surname as a
> \startluacode
> local a = {'null-terminated', 'dollar-terminated', 'Pascal'}
> context('%s string', a[math.random(1,3)])
> \stopluacode
> \stoptext
> -------------------------------------------------------------
> How can I randomize this?

Hmm... which version are you using?  I do get a ranom output each time.
Tested with 2009.12.31 and  2010.03.20.

Since the math seed is set after \starttext, it should overwrite the value 
after reading the tuc file.

Actually, I consider saving the random number in tuc file to be a 
misfeature. A random sequence generator should generate a random sequence. 
If I want the same behavior all the time, I can use 
\setupsystem[random=12345] (which should also set 
math.randomseed).

Aditya
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Re: randomize

[Wolfgang Werners-Lucchini]

> Am 06.04.10 00:21, schrieb Wolfgang Werners-Lucchini:
> > Hallo,
> >
> > I get allways (10 times at least) the same result:
> > -------------------------------------------------------------
> > \starttext
> > \startluacode
> > math.randomseed(os.time())
> > \stopluacode
> >
> > Encode your Name and Surname as a
> > \startluacode
> > local a = {'null-terminated', 'dollar-terminated', 'Pascal'}
> > context('%s string', a[math.random(1,3)])
> > \stopluacode
> > \stoptext
> > -------------------------------------------------------------
> > How can I randomize this?
> >    
> ConTeXt saves the random value in the tuc file to get the same
> output in 
> each run.
> 
> Delete the tuc file with 'context --purgeall'.

This does not work! I get allways the same.

And shouldn't the tuc-seed be overwriten from my os.time-seed?

Wolfgang
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Re: randomize

[Wolfgang Schuster]

Am 06.04.10 00:21, schrieb Wolfgang Werners-Lucchini:
> Hallo,
>
> I get allways (10 times at least) the same result:
> -------------------------------------------------------------
> \starttext
> \startluacode
> math.randomseed(os.time())
> \stopluacode
>
> Encode your Name and Surname as a
> \startluacode
> local a = {'null-terminated', 'dollar-terminated', 'Pascal'}
> context('%s string', a[math.random(1,3)])
> \stopluacode
> \stoptext
> -------------------------------------------------------------
> How can I randomize this?
>    
ConTeXt saves the random value in the tuc file to get the same output in 
each run.

Delete the tuc file with 'context --purgeall'.

Wolfgang

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randomize

[Wolfgang Werners-Lucchini]

Hallo,

I get allways (10 times at least) the same result:
-------------------------------------------------------------
\starttext
\startluacode
math.randomseed(os.time())
\stopluacode

Encode your Name and Surname as a
\startluacode
local a = {'null-terminated', 'dollar-terminated', 'Pascal'}
context('%s string', a[math.random(1,3)])
\stopluacode
\stoptext
-------------------------------------------------------------
How can I randomize this?

Wolfgang
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