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Groups > comp.lang.python > #71506

Re: Fortran

From Alain Ketterlin <alain@dpt-info.u-strasbg.fr>
Newsgroups comp.lang.python
Subject Re: Fortran
Date 2014-05-13 19:33 +0200
Organization Universites Paris VI/Paris VII - France
Message-ID <871tvxtwgj.fsf@dpt-info.u-strasbg.fr> (permalink)
References (12 earlier) <lkn4mh$4d5$1@speranza.aioe.org> <87mweotfe5.fsf@dpt-info.u-strasbg.fr> <lkoh14$rpq$1@speranza.aioe.org> <87iopbtmh1.fsf@dpt-info.u-strasbg.fr> <lksarq$n5r$1@speranza.aioe.org>

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Mark H Harris <harrismh777@gmail.com> writes:

> On 5/12/14 3:44 AM, Alain Ketterlin wrote:

>> When you are doing scientific computation, this overhead is
>> unacceptable, because you'll have zillions of computations to perform.
>
>     I'm still trying to sort that out. I have not tested this yet, but
> it looks like Julia is fully dynamic (yes it has types too), and it
> does parallel processing at its core, so the zillions of computations
> are being handled all at once, depending on how many processors|cores
> you have.

The amount of parallelism is a property of the program, not a property
of the language... I hope you don't expect all your julia statements to
execute in parallel.

(And Fortan/C/C++ have leveraged OpenMP and MPI for years. Julia's
distributed arrays and fork-join model may make things a bit easier for
the programmer, but I doubt it will lead to better performance.)

>> Julia provides a way to make things fast: typing. If you provide
>> explicit types, the dynamic typing part obviously disappears, and
>> the overhead is removed.
>
>     Julia is dynamic (depending on how far you want to go with that)
> but what makes it fast is the JIT. It is almost accomplishing C/C++
> and FORTRAN speeds (even though dynamic) because it is compiling
> on-the-fly.

JITing by itself has little impact on performance (as unladden-swallow
has shown for python). For the JIT to produce code as fast as a
Fortan/C/C++ compiler would, two conditions must be met: 1) the JIT has
to have as much information about types as the statically-typed language
compilers have, and 2) the time spent by the JIT compiler has to be
negligible compared to the time spent executing the code.

If your program is not statically typed, the code produced by the JIT is
very unlikely to be more efficient than the code that would be executed
by the virtual machine (or interpreter), because the jitted code needs
to do everything the virtual machine does. And the JIT takes time.

[...]
>     Yes, and more+  Gnu GMP & MPFR are not new to me, but the wrapper
> and repl are !  I am just realizing the power behind the libraries in
> this context, but I am very impressed with the functionality wrapped
> around the Gnu stuff... the interface is quite nice.

Good. I don't know mathlab enough to see how it compares.

>> Sorry, I was comparing to Fortran, and it's use in scientific computing.
>> Self modifying code is totally irrelevant there.
>
>    no, no, no...  there has to be a value add for scientists to move
> away from R or Matlab, or from FORTRAN. Why go to the trouble?
[...]
>    Why?, glad you asked.  Enter self modifying code for one. The
> influence of Lisp|Scheme is potentially huge here.

I wouldn't bet a penny on this. (Probably because I have yet to see a
real, convincing application of self-modifying code. I mean something
which is not covered by JITs---GPU shaders, and things like that.)

The real nice thing that makes Julia a different language is the
optional static typing, which the JIT can use to produce efficient code.
It's the only meaningful difference with the current state of python.

-- Alain.

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Re: The “does Python have variables?” debate Ned Batchelder <ned@nedbatchelder.com> - 2014-05-06 21:19 -0400
  Re: The “does Python have variables?” debate Marko Rauhamaa <marko@pacujo.net> - 2014-05-07 09:18 +0300
    Re: The “does Python have variables?” debate Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-05-07 09:51 +0100
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            Re: The “does Python have variables?” debate Mark H Harris <harrismh777@gmail.com> - 2014-05-07 16:35 -0500
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                Re: Fortran (Was: The "does Python have variables?" debate) Terry Reedy <tjreedy@udel.edu> - 2014-05-10 14:31 -0400
                Re: Fortran (Was: The "does Python have variables?" debate) Mark H Harris <harrismh777@gmail.com> - 2014-05-11 01:17 -0500
                Re: Fortran (Was: The "does Python have variables?" debate) Rustom Mody <rustompmody@gmail.com> - 2014-05-11 00:01 -0700
                Re: Fortran (Was: The "does Python have variables?" debate) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 07:09 +0000
                Re: Fortran (Was: The "does Python have variables?" debate) Tomasz Rola <rtomek@ceti.pl> - 2014-05-11 18:09 +0200
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                Re: Fortran Roy Smith <roy@panix.com> - 2014-05-11 13:51 -0400
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                Re: Fortran Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-12 02:28 +0000
                Re: Fortran Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-05-12 10:05 +0100
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                Re: Fortran Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 23:15 +0000
                Re: Fortran MRAB <python@mrabarnett.plus.com> - 2014-05-12 00:51 +0100
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                Re: Fortran alister <alister.nospam.ware@ntlworld.com> - 2014-05-12 14:14 +0000
                Re: Fortran Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-12 01:11 +0000
                Re: Fortran Dave Angel <d@davea.name> - 2014-05-11 23:27 -0400
                Re: Fortran Grant Edwards <invalid@invalid.invalid> - 2014-05-12 14:07 +0000
                Re: Fortran Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-05-11 21:12 -0400
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                Re: Fortran Tomasz Rola <rtomek@ceti.pl> - 2014-05-11 20:04 +0200
                Re: Fortran Chris Angelico <rosuav@gmail.com> - 2014-05-12 04:12 +1000
                Re: Fortran (Was: The "does Python have variables?" debate) Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-05-11 19:05 +0200
                Re: Fortran (Was: The "does Python have variables?" debate) Mark H Harris <harrismh777@gmail.com> - 2014-05-11 13:54 -0500
                Re: Fortran (Was: The "does Python have variables?" debate) Chris Angelico <rosuav@gmail.com> - 2014-05-12 04:59 +1000
                Re: Fortran (Was: The "does Python have variables?" debate) Mark H Harris <harrismh777@gmail.com> - 2014-05-11 14:14 -0500
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                Re: Fortran (Was: The "does Python have variables?" debate) Peter Pearson <ppearson@nowhere.invalid> - 2014-05-29 17:53 +0000
                Re: Fortran (Was: The "does Python have variables?" debate) Dave Angel <davea@davea.name> - 2014-05-11 23:10 -0400
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                Re: Fortran (Was: The "does Python have variables?" debate) Mark H Harris <harrismh777@gmail.com> - 2014-05-11 23:26 -0500
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                Re: Fortran (Was: The "does Python have variables?" debate) Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-05-12 10:44 +0200
                Re: Fortran (Was: The "does Python have variables?" debate) Mark H Harris <harrismh777@gmail.com> - 2014-05-13 00:33 -0500
                Re: Fortran (Was: The "does Python have variables?" debate) Steven D'Aprano <steve@pearwood.info> - 2014-05-13 05:48 +0000
                Re: Fortran (Was: The "does Python have variables?" debate) Mark H Harris <harrismh777@gmail.com> - 2014-05-13 00:55 -0500
                Re: Fortran (Was: The "does Python have variables?" debate) Chris Angelico <rosuav@gmail.com> - 2014-05-13 15:56 +1000
                Re: Fortran (Was: The "does Python have variables?" debate) Steven D'Aprano <steve@pearwood.info> - 2014-05-13 09:34 +0000
                Re: Fortran (Was: The "does Python have variables?" debate) Chris Angelico <rosuav@gmail.com> - 2014-05-13 20:00 +1000
                Re: Fortran (Was: The "does Python have variables?" debate) Rustom Mody <rustompmody@gmail.com> - 2014-05-13 03:44 -0700
                Re: Fortran (Was: The "does Python have variables?" debate) Chris Angelico <rosuav@gmail.com> - 2014-05-13 20:50 +1000
                Re: Fortran (Was: The "does Python have variables?" debate) Gene Heskett <gheskett@wdtv.com> - 2014-05-13 02:31 -0400
                Re: Fortran (Was: The "does Python have variables?" debate) Steven D'Aprano <steve@pearwood.info> - 2014-05-13 07:22 +0000
                Re: Fortran (Was: The "does Python have variables?" debate) Roy Smith <roy@panix.com> - 2014-05-13 07:16 -0400
                Re: Fortran (Was: The "does Python have variables?" debate) Chris Angelico <rosuav@gmail.com> - 2014-05-13 21:21 +1000
                Re: Fortran (Was: The "does Python have variables?" debate) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-05-13 14:42 +0100
                Re: Fortran (Was: The "does Python have variables?" debate) Gene Heskett <gheskett@wdtv.com> - 2014-05-13 07:42 -0400
                Re: Fortran Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-05-13 19:33 +0200
                Re: Fortran Marko Rauhamaa <marko@pacujo.net> - 2014-05-13 22:57 +0300
                Re: Fortran Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-14 00:10 +0000
                Re: Fortran Ian Kelly <ian.g.kelly@gmail.com> - 2014-05-13 21:43 -0600
                Re: Fortran Marko Rauhamaa <marko@pacujo.net> - 2014-05-14 07:35 +0300
                Re: Fortran Steven D'Aprano <steve@pearwood.info> - 2014-05-14 06:58 +0000
                Re: Fortran Marko Rauhamaa <marko@pacujo.net> - 2014-05-14 11:46 +0300
                Re: Fortran Sturla Molden <sturla.molden@gmail.com> - 2014-05-14 23:05 +0000
                struct.unpack: why 's' fmt char convert to bytestring GuoChao <cx63@outlook.com> - 2014-05-15 20:34 +0800
                Re: struct.unpack: why 's' fmt char convert to bytestring Dave Angel <davea@davea.name> - 2014-05-15 09:49 -0400
                Re: struct.unpack: why 's' fmt char convert to bytestring MRAB <python@mrabarnett.plus.com> - 2014-05-15 15:47 +0100
                Re: Fortran Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-05-14 15:13 +0200
                Re: Fortran albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-05-29 14:26 +0000
                Re: Fortran Marko Rauhamaa <marko@pacujo.net> - 2014-05-29 17:50 +0300
                Re: Fortran Chris Angelico <rosuav@gmail.com> - 2014-05-30 00:58 +1000
                Re: Fortran Marko Rauhamaa <marko@pacujo.net> - 2014-05-29 18:09 +0300
                Re: Fortran Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-29 17:57 +0000
                Re: Fortran Marko Rauhamaa <marko@pacujo.net> - 2014-05-29 21:55 +0300
                Re: The “does Python have variables?” debate Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-05-09 09:13 +0100
                Re: The “does Python have variables?” debate Michael Torrie <torriem@gmail.com> - 2014-05-08 08:06 -0600
                Re: The “does Python have variables?” debate Chris Angelico <rosuav@gmail.com> - 2014-05-09 00:13 +1000
            Re: The “does Python have variables?” debate Terry Reedy <tjreedy@udel.edu> - 2014-05-08 15:21 -0400
              Re: The “does Python have variables?” debate Marko Rauhamaa <marko@pacujo.net> - 2014-05-08 23:06 +0300
                Re: The “does Python have variables?” debate Ethan Furman <ethan@stoneleaf.us> - 2014-05-08 15:36 -0700
            Re: The “does Python have variables?” debate Ethan Furman <ethan@stoneleaf.us> - 2014-05-08 17:05 -0700
            Re: The “does Python have variables?” debate Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-05-09 01:47 +0100
      Re: The “does Python have variables?” debate Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-08 00:57 +0000
      Re: The “does Python have variables?” debate Roy Smith <roy@panix.com> - 2014-05-08 08:41 -0400
        Re: The “does Python have variables?” debate Chris Angelico <rosuav@gmail.com> - 2014-05-08 22:54 +1000
        Re: The “does Python have variables?” debate Ethan Furman <ethan@stoneleaf.us> - 2014-05-08 06:18 -0700
          Re: The “does Python have variables?” debate Marko Rauhamaa <marko@pacujo.net> - 2014-05-08 17:03 +0300
            Re: The “does Python have variables?” debate Ethan Furman <ethan@stoneleaf.us> - 2014-05-08 16:09 -0700
        Re: The “does Python have variables?” debate "Neil D. Cerutti" <neilc@norwich.edu> - 2014-05-08 10:47 -0400

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