Re: [gentoo-user] Re: OT Best way to compress files with digits

[Alan McKinnon]

On 01/11/2014 19:59, meino.cramer@×××.de wrote:
> James <wireless@×××××××××××.com> [14-11-01 18:16]:
>>  <meino.cramer <at> gmx.de> writes:
>>
>>
>>>  I have a lot of files with digits of PI. The digits
>>>  are the characters of 0-9. Currently they are ZIPped,
>>>  which I think is not the best way to do that.
>>
>> Hello Meino,
>>
>> It's a bit of effort, but the world's recognized authority
>> on algorithms is Don Knuth. [1] He's old now, but his
>> pioneering attempt at categorizing most algorithms:
>> "The art of computer programming" and his MMIX alogrithm
>> implementations (kinda like assembler) are certainly
>> part of many first-step research efforts on algorithms
>> and their implementations.
>>
>> It's not a cookbook; more of a scholarly (high_brow) reference,
>> just to supplement all the good postings by your peers on gentoo user.
>>
>> Alan may loan you his copy?
>> (ha ha ha)?
>>
>>
>>
>> hth,
>> James
>>
>> [1] http://www-cs-faculty.stanford.edu/~uno/
>>
>
> Hello james,
>
> Don Knuth ... oh YES! :)
> For a long time I am using and prefering TeX over anything else
> (ok...for ASCII I use vim... ;).
>
> And beside his computer wisdom I also like his kind of humor a lot...
> for example this one:
> https://www.youtube.com/watch?v=eKaI78K_rgA&list=PLUu0XRts4lK6Ri7-xaCNYqTHx7We95Rk8&index=10
>
> But my initial question was more targeted to "practical computing" as
> to groundshakeing and fundamental research topics.
>
> More like "what tool to pick?"...
>
> I did some compression tests myself and currently I have this:
>>From http://piworld.calico.jp/ (http://piworld.calico.jp/estart.html)
> I got zipped package of
> 1000 million places of PI each (~57MB for one ZIP).
>
> I unpacked the first package and recompressed it with different
> methods of 7zip, gzip and bzip2. For gzip and bzip2 I used the highest
> compression mode (-9). When a files name matches /.*ultra.*/, I used
> the highest compression mode (-mx=9), else I only set the compression
> method and leave the rest untouched (defaults).
>
>
>  119888896 2014-10-31 16:44 pi-0001.txt
>   57105419 2014-10-31 16:47 pi-0001.txt.gz
>   52632832 2014-10-31 16:48 pi-0001.txt.bz2
>   52045827 2014-10-31 16:54 pi-0001.txt.ppmd.7z
>   57110291 2014-10-31 17:23 pi-0001.zip
>   51766683 2014-10-31 17:26 pi-0001.txt.lzma.7z
>   51668838 2014-10-31 17:34 pi-0001.txt.lzma.ultra.7z
>   52862115 2014-10-31 17:36 pi-0001.txt.ppmd.ultra.7z
>   51668838 2014-10-31 17:39 pi-0001.txt.ultra.7z
>
> 7zip's lzma wins here, which is also the default method of 7zip. I set
> the ultra mode for this by hand.
>
>>From other sites which offer PI for download I know of methods, which
> store the ASCII-digits in binary and compresses then. Would be
> interesting, whether this creates a more "handy" input from 7zips
> point of view...
>
> Ah! By the way...I was astonished to read, that the digits of PI are
> called random on the one hand and on the other hand there is a formula [1]
> to calculate a certain digit of PI without calculation of the previous
> digits...
> Calculated random? Are nature constants the purest form of PRNGs ??? ;)
> (Quantum physics is everywhere... ;;))
>
> [1]: http://en.wikipedia.org/wiki/Bailey%E2%80%93Borwein%E2%80%93Plouffe_formula


The sequence of digits that make up pi are a random sequence - you can
analyze the order any way you want and you'll find no inherent pattern.
However, any given digit in the sequence is 100% predictable, as you
just showed :-)

Randomness has got to be the second most mind-boggling thing out there,
first being quantumness (that's not a waord, I just made it up. You you
should get the meaning OK from context ;-) )

-- 
Alan McKinnon
alan.mckinnon@×××××.com