[issue26256] Fast decimalisation and conversion to other bases

Change by Stefan Krah : -- assignee: docs@python -> skrah resolution: -> fixed stage: patch review -> resolved status: open -> closed ___ Python tracker ___

[issue26256] Fast decimalisation and conversion to other bases

Stefan Krah added the comment: New changeset a2f4c4023314f69333d2e8cee68e316619f3d68e by Stefan Krah (Miss Islington (bot)) in branch '3.7': bpo-26256: Document algorithm speed for the Decimal module. (GH-4808) (#11736)

[issue26256] Fast decimalisation and conversion to other bases

Change by miss-islington : -- pull_requests: +11639, 11640, 11641 ___ Python tracker ___ ___ Python-bugs-list mailing list

[issue26256] Fast decimalisation and conversion to other bases

Change by miss-islington : -- pull_requests: +11639 ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue26256] Fast decimalisation and conversion to other bases

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[issue26256] Fast decimalisation and conversion to other bases

Stefan Krah added the comment: New changeset 00e9c55d27aff3e445ab4c8629cf4d59f46ff945 by Stefan Krah (Cheryl Sabella) in branch 'master': bpo-26256: Document algorithm speed for the Decimal module. (#4808) https://github.com/python/cpython/commit/00e9c55d27aff3e445ab4c8629cf4d59f46ff945

[issue26256] Fast decimalisation and conversion to other bases

Cheryl Sabella added the comment: ping -- ___ Python tracker ___ ___ Python-bugs-list

[issue26256] Fast decimalisation and conversion to other bases

Change by Cheryl Sabella : -- versions: +Python 3.7 -Python 3.4 ___ Python tracker ___

[issue26256] Fast decimalisation and conversion to other bases

Change by Cheryl Sabella : -- keywords: +patch pull_requests: +4704 stage: -> patch review ___ Python tracker ___

[issue26256] Fast decimalisation and conversion to other bases

Stefan Krah added the comment: What needs to be mentioned though is that the context has to be set for unrounded calculations: c = getcontext() c.prec = MAX_PREC c.Emax = MAX_EMAX c.Emin = MIN_EMIN Otherwise some people believe that the bignums are just rounded floating point arithmetic that

[issue26256] Fast decimalisation and conversion to other bases

Stefan Krah added the comment: pypy-5.8.0-beta0 (Python 3.5.3) is using a very nicely written CFFI wrapper for libmpdec, so it also has the fast bignums. -- ___ Python tracker

[issue26256] Fast decimalisation and conversion to other bases

Raymond Hettinger added the comment: A couple of thoughts: * It is okay to add a couple lines to the decimal module docs noting a Cpython specific implementation detail that it uses better than expected algorithms which can payoff nicely when used with very large numbers. * Mersenne prime

[issue26256] Fast decimalisation and conversion to other bases

Cheryl Sabella added the comment: Hello, I came across this issue and was wondering if the FAQ section of the doc might be a good place to mention the presence of FFT, or actually fast number theoretic transform, as Stefan pointed out. I was also wondering if the short code snippet for the

[issue26256] Fast decimalisation and conversion to other bases

Jurjen N.E. Bos added the comment: That reference you gave says that the binary version is faster than the Python version, but here the _complexity_ actually changed by a lot. Only people who know the library by name will notice that it is this fast. But you are right, for 99% of the people it

[issue26256] Fast decimalisation and conversion to other bases

Jurjen N.E. Bos added the comment: OMG is decimal that fast? Maybe I should change the issue then to "documentation missing": it nowhere says in the documentation that decimal has optimized multiprecision computations. It only says that precision "can be as large as needed for a given

[issue26256] Fast decimalisation and conversion to other bases

Stefan Krah added the comment: On Wed, Feb 03, 2016 at 09:51:53AM +, STINNER Victor wrote: > Well, nowhere means: > https://docs.python.org/dev/whatsnew/3.3.html#decimal Okay, but hardly anyone reads that, and I can't blame them. :) For example, if I use something like Lua, I won't read a

[issue26256] Fast decimalisation and conversion to other bases

STINNER Victor added the comment: "It's great to have this stuff, but I don't think it belongs in core Python: I'd much rather that the core Python integer implementation remain simple, portable and low-maintenance, and work well for the domain it's intended for: small-to-medium size

[issue26256] Fast decimalisation and conversion to other bases

Mark Dickinson added the comment: Not really the same, since that issue was more about fast division. But it's the same spirit. It looks like I was more enthusiastic back then; now I'm older and grumpier. It's great to have this stuff, but I don't think it belongs in core Python: I'd much

[issue26256] Fast decimalisation and conversion to other bases

Stefan Krah added the comment: Jurjen, this is very nice! -- Like Mark, I'm not sure if this should be in CPython. Decimal (Python >= 3.3) has sneaked in a couple of fast bignum algorithms, so calculating and converting the latest Mersenne prime takes a couple of seconds: from decimal import

[issue26256] Fast decimalisation and conversion to other bases

Serhiy Storchaka added the comment: Is this the same algorithm as in issue3451? -- nosy: +serhiy.storchaka ___ Python tracker ___

[issue26256] Fast decimalisation and conversion to other bases

New submission from Jurjen N.E. Bos: Inspired by the recently new discovered 49th Mersenne prime number I wrote a module to do high speed long/int to decimal conversion. I can now output the new Mersenne number in 18.5 minutes (instead of several hours) on my machine. For numbers longer than

[issue26256] Fast decimalisation and conversion to other bases

Mark Dickinson added the comment: Very nice. I'd suggest posting it as a recipe or as a Python package on PyPI for others to use. It's not really something that it would be appropriate to add to the Python core: Python isn't really intended for super-efficient high-precision arithmetic, and

[issue26256] Fast decimalisation and conversion to other bases

Jurjen N.E. Bos added the comment: Thanks for the tip. I'll consider making it a recipe. - Jurjen -- ___ Python tracker ___