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Postings from August 2010
On 21.08.2010 13:46, demerphq wrote:
> On 21 August 2010 12:52, Wolfram Humann<w.c.humann@arcor.de> wrote:
>
>
>> perl -MData::Dumper -E"sub mt{my $d=shift;$d>0?[mt($d-1),mt($d-1)]:int rand
>> 100}; say length Dumper mt 18"
>> 34576966
>>
>> needs approx. 6 seconds to print and 8 seconds to finish on both of these.
>>
> Interesting, how does that compare for you if you stick a
>
> $Data::Dumper::Useqq=1;
>
> before the dump?
Some more results, wristwatch timed -> ignore minor differences:
N=20
strawberry: 27 seconds
with my patch: 29 seconds
usemymalloc: 10 seconds
With $Data::Dumper::Useqq=1 I had to reduce N to 19 to avoid
out-of-memory. Strawberryperl unpatched only.
Without $Data::Dumper::Useqq=1: 10 seconds, 462 MB
With $Data::Dumper::Useqq=1: 28 seconds, 1100 MB
>> No noticeable difference. With a touch of horror I have to report that the
>> printed stringlengths are slightly non-deterministic from run to run...???
>>
> :-)
>
> No worries there, the code does use rand() after all, so we expect to
> see slightly different results from run to run (or the srand
> initialization would be broken). Add a srand(1) or change the int rand
> 100 to a constant and it should produce repeatable results.
>
O.k. so no need to be worried about the code. But maybe I need to be
worried about a mind that is obvously able to type "rand" one moment and
complain about the code running non-deterministic about 5 minutes later ;-)
I'll be on vacation soon. Won't be able to respond to news in this
thread quickly (maybe not at all) for the weeks to come.
Wolfram
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