- **Perl Misc**
(*http://www.velocityreviews.com/forums/f67-perl-misc.html*)

- - **Math**
(*http://www.velocityreviews.com/forums/t903888-math.html*)

MathI realize that any math in Perl is probably slower than the same math
in "C" but I was wondering if Perl was as accurate as "C" in math computations. I don't see why it wouldn't be but I thought I would ask as a heavy spherical math project is on the horizon. Robert |

Re: MathRobert Hicks wrote:
> I realize that any math in Perl is probably slower than the same math > in "C" but I was wondering if Perl was as accurate as "C" in math > computations. It's all the same arithmetic under the covers. But it /will/ be slower, if pure compute time is the bottleneck. -- John W. Kennedy "The poor have sometimes objected to being governed badly; the rich have always objected to being governed at all." -- G. K. Chesterton. "The Man Who Was Thursday" |

Re: MathRobert Hicks wrote:
> I realize that any math in Perl is probably slower than the same math > in "C" but I was wondering if Perl was as accurate as "C" in math > computations. Computational precision depends on many factors like e.g. underlying hardware, OS architecture, standard libraries, compiler/interpreter optimization, etc. But it has nothing to do with the actual programming language(*). jue (*): well, at least as long as we exclude symbolic computations in specialized mathematical programming languages. |

Re: MathRobert Hicks wrote:
> I realize that any math in Perl is probably slower than the same math > in "C" but I was wondering if Perl was as accurate as "C" in math > computations. I don't see why it wouldn't be but I thought I would ask > as a heavy spherical math project is on the horizon. From my own experiences: Perl is not *that* slow in numerical thinks. The speed-problem will show up if you do some matrix or vector stuff in naíve Perl expressions because the array handling is somehow expensive then. The "accuracy" is, as has been mentioned, in the normal IEEE "double" range. With only one additional line of code (eg. "use Math::BigFloat;"), one can get into almost "arbitary accuracy" mode (see: http://perldoc.perl.org/Math/BigFloat.html and others). There is already a Perl extension for vector and matrix computations, it's called 'PDL' (Perl Data language, see http://pdl.perl.org/) an an implementation of GNU-GMP's mpf routines (http://search.cpan.org/~sisyphus/Math-GMPf-0.14/GMPf.pm) To get a clearer picture for startup, read: http://math.arizona.edu/~kerl/doc/perl-talk.pdf Regards M. |

Re: MathOn Thu, 19 Jul 2007 08:36:50 +0200, Mirco Wahab
<wahab@chemie.uni-halle.de> wrote: >There is already a Perl extension for vector and matrix >computations, it's called 'PDL' (Perl Data language, >see http://pdl.perl.org/) an an implementation of Since documentation seems not to abound, it is worth mentioning, for the interested reader, that "lino" is posting a number of articles and snippets about it in PerlMonks: the following Super Search should retrieve them; note that it doesn't bring you directly to the results but simply preloads some search form fields. http://perlmonks.org/?node_id=3989;BIT=pdl;a=lin0 Michele -- {$_=pack'B8'x25,unpack'A8'x32,$a^=sub{pop^pop}->(map substr (($a||=join'',map--$|x$_,(unpack'w',unpack'u','G^<R<Y]*YB=' ..'KYU;*EVH[.FHF2W+#"\Z*5TI/ER<Z`S(G.DZZ9OX0Z')=~/./g)x2,$_, 256),7,249);s/[^\w,]/ /g;$ \=/^J/?$/:"\r";print,redo}#JAPH, |

Re: MathOn Thu, 19 Jul 2007 01:46:54 -0000, Robert Hicks <sigzero@gmail.com>
wrote: >Subject: Math Maths! >I realize that any math in Perl is probably slower than the same math >in "C" but I was wondering if Perl was as accurate as "C" in math >computations. I don't see why it wouldn't be but I thought I would ask >as a heavy spherical math project is on the horizon. With the usual caveat about "many parameters to take into account", there shouldn't be a difference, but possibly for a Perl's dwimmery not really doing what you want. And when accuracy becomes a relevant issue, then you can use specialized packages, as hinted to by others. Michele -- {$_=pack'B8'x25,unpack'A8'x32,$a^=sub{pop^pop}->(map substr (($a||=join'',map--$|x$_,(unpack'w',unpack'u','G^<R<Y]*YB=' ..'KYU;*EVH[.FHF2W+#"\Z*5TI/ER<Z`S(G.DZZ9OX0Z')=~/./g)x2,$_, 256),7,249);s/[^\w,]/ /g;$ \=/^J/?$/:"\r";print,redo}#JAPH, |

Re: Math"Mirco Wahab" <wahab@chemie.uni-halle.de> wrote in message news:f7n0q3$26ae$1@nserver.hrz.tu-freiberg.de... > Robert Hicks wrote: >> I realize that any math in Perl is probably slower than the same math >> in "C" but I was wondering if Perl was as accurate as "C" in math >> computations. I don't see why it wouldn't be but I thought I would ask >> as a heavy spherical math project is on the horizon. > > From my own experiences: Perl is not *that* slow in > numerical thinks. I'll (tentatively) agree with that. > > The "accuracy" is, as has been mentioned, in the > normal IEEE "double" range. With only one additional > line of code (eg. "use Math::BigFloat;"), one can get > into almost "arbitary accuracy" mode > (see: http://perldoc.perl.org/Math/BigFloat.html and others). > But now things *do* start to get noticeably slower ... to the extent that a "heavy spherical math project" may be better advised to use (instead of Math::BigFloat) Math::Pari or <plug> Math::MPFR </plug>, both of which make extensive use of "C" computations. Of course, it all depends upon the heaviness and sphericality of the math project :-) Cheers, Rob |

Re: MathOn Fri, 20 Jul 2007 01:33:52 +1000, "Sisyphus"
<sisyphus1@nomail.afraid.org> wrote: >But now things *do* start to get noticeably slower ... to the extent that a >"heavy spherical math project" may be better advised to use (instead of >Math::BigFloat) Math::Pari or <plug> Math::MPFR </plug>, both of which make >extensive use of "C" computations. I was about to tell you that M::BF can use a suitable XS module, if you tell it so: but I checked and it's not the case, although it definitely is with M::BI. Too bad... Michele -- {$_=pack'B8'x25,unpack'A8'x32,$a^=sub{pop^pop}->(map substr (($a||=join'',map--$|x$_,(unpack'w',unpack'u','G^<R<Y]*YB=' ..'KYU;*EVH[.FHF2W+#"\Z*5TI/ER<Z`S(G.DZZ9OX0Z')=~/./g)x2,$_, 256),7,249);s/[^\w,]/ /g;$ \=/^J/?$/:"\r";print,redo}#JAPH, |

Re: MathThank you and thanks for all the answers.
Robert |

Re: MathMichele Dondi <bik.mido@tiscalinet.it> wrote:
> On Thu, 19 Jul 2007 01:46:54 -0000, Robert Hicks <sigzero@gmail.com> > wrote: > >Subject: Math > Maths! Math! If you need an `s' at the end, it's mathematics! > >I realize that any math in Perl is probably slower than the same math > >in "C" but I was wondering if Perl was as accurate as "C" in math > >computations. I don't see why it wouldn't be but I thought I would ask > >as a heavy spherical math project is on the horizon. > With the usual caveat about "many parameters to take into account", > there shouldn't be a difference, but possibly for a Perl's dwimmery > not really doing what you want. And when accuracy becomes a relevant > issue, then you can use specialized packages, as hinted to by others. Yeah, everyone has pretty much indicated the problems here, but I'll echo the "it depends on what you're doing". I'm not the expert, but I have my own arbitrary precision stuff in perl and it's slow, but that's okay because it is supposed to be slow (figure that one out). On the other hand, my C matrix routines are faster than PARI. In my experience, perl is generally slower for heavy number crunching, but it does well enough if only 25% of your code really has anything to do with a bunch of numerical processing. If all that processing is driving some other frontend, then it seems to fair pretty well. -- Brian Blackmore blb8 at po dot cwru dot edu |

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