From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,19924f2facf8443 X-Google-Attributes: gid103376,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news1.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsfeed.velia.net!noris.net!newsfeed.arcor.de!newsspool3.arcor-online.net!news.arcor.de.POSTED!not-for-mail Date: Fri, 08 Aug 2008 17:40:16 +0200 From: Georg Bauhaus User-Agent: Thunderbird 2.0.0.16 (Macintosh/20080707) MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Larger matrices References: <40ed91c2-3dab-4994-9a7b-4032058f0671@56g2000hsm.googlegroups.com> <4899b545$0$20713$9b4e6d93@newsspool4.arcor-online.net> <96f76821-fc2a-4ec1-83e7-b7b9a5be0520@r66g2000hsg.googlegroups.com> <9cabee20-877a-4fdc-80f8-7746879331da@8g2000hse.googlegroups.com> <489a9675$0$20718$9b4e6d93@newsspool4.arcor-online.net> <75a339dd-969b-4c7a-8e89-7b640171bc2f@e53g2000hsa.googlegroups.com> <13426f2d-0060-47f0-8139-09506383f648@e53g2000hsa.googlegroups.com> <489c2f68$0$1060$9b4e6d93@newsspool3.arcor-online.net> <489c542e$0$12944$9b4e6d93@newsspool2.arcor-online.net> <1d0ueuhuo8z2e.ewzvifms2lau$.dlg@40tude.net> In-Reply-To: <1d0ueuhuo8z2e.ewzvifms2lau$.dlg@40tude.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Message-ID: <489c68e1$0$12941$9b4e6d93@newsspool2.arcor-online.net> Organization: Arcor NNTP-Posting-Date: 08 Aug 2008 17:40:17 CEST NNTP-Posting-Host: 6486c109.newsspool2.arcor-online.net X-Trace: DXC=6lSA\E7ZB^DI7\_^6>c20JA9EHlD;3YcB4Fo<]lROoRA4nDHegD_]REPN3cBXB]mZC;9OJDO8_SKFNSZ1n^B98iJc Dmitry A. Kazakov schrieb: > They are not. Lisp is a list-oriented language, Prolog is a logical > inference language. Lisp and Prolog with FFI(!) are not universal? Come on. >> This notion of "purpose" is not very specific. >> Let me put is this way: Ada has to be especially good at >> systems programming, hence it has to be fairly low level. > > Wrong. Where that follows from? Systems programming need not to be > low-level. A systems programming language must provide for the low level. A language that does not provide for the low level is not a systems programming language. Ada has many features that provide for low level programming. It lacks a numer of features used in higher level programming (E.g. function environments, unbounded numbers, ...). Systems programming is not the same as low level programming or high level programming; rather, the set of objects is typically not as abstract as some mathematical N-array of numbers. The set of objects in a systems programming language is more like a real N-array of numbers: storage cells of well defined meaning, with just one layer of abstraction above the storage cells. >> What hardware? > > Vector processors. OK, I wasn't aware that the LA packages were made for vector processors only. >> Assume data flow hardware, and assume a way >> to put the function result in the input box of the next processing unit. >> What now? > > Nothing, Ada.Numerics.Generic_Real_Arrays was not designed in order to > support this hardware. Aha? I see that GNAT delegates to Fortran libraries. Traditionally, Fortran is certainly an associate of non-PC hardware. > Which is the point. Ada is not low-level, Ada is fairly low-level. >> I don't see how prototyping a hypertext graph algorithm >> requires a maximally efficient implementation of matrix >> computations. > > Because of the problem size. Incidence matrices grow as O(n**2), i.e. > extremely fast. O(N**2) is not extremely fast; many non-extreme algorithms are in this class. The case discussed hits some memory barrier at n = 5_000 and that's it. We get elaborate array indexing support in some array programming languages. If chosing one of those PLs costs me a constant factor of 10, I get all the indexing stuff in return, it seems worth the cost during prototyping. >> A production system may require increased >> efficiency. At that stage you have to pay attention to >> the tiny bits, possibly redesigning the algorithm. > > Numerics is all about algorithms. Numerics is about numbers (or about numeric control, depending). > This BTW is exactly the problem OP has. He has "prototyped" the thing using > Ada.Numerics.Generic_Real_Arrays. Now, he faces the problem that the > prototype does not scale due to stack overflow. The consequence is a need > in full redesign. Ergo, prototyping was time wasting. Nice rhetoric logic error. -- Georg Bauhaus Y A Time Drain http://www.9toX.de