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,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,8c8550b9f2cf7d40 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-06-08 21:24:36 PST Path: archiver1.google.com!postnews1.google.com!not-for-mail From: 18k11tm001@sneakemail.com (Russ) Newsgroups: comp.lang.ada Subject: Re: Is ther any sense in *= and matrices? Date: 8 Jun 2003 21:24:36 -0700 Organization: http://groups.google.com/ Message-ID: References: NNTP-Posting-Host: 63.194.87.148 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: posting.google.com 1055132676 18484 127.0.0.1 (9 Jun 2003 04:24:36 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: 9 Jun 2003 04:24:36 GMT Xref: archiver1.google.com comp.lang.ada:38843 Date: 2003-06-09T04:24:36+00:00 List-Id: tmoran@acm.org wrote in message news:... > >Oh, really? I just did a test in C++ with 3x3 matrices. I added them > >together 10,000,000 times using "+", then "+=". The "+=" version took > >about 19 seconds, and the "+" version took about 55 seconds. That's > Would you be so kind as to post your code, and what C++ compiler > and what hardware you used? Your results seem quite different from > other people's. My old 900MHz Windows 2K machine using MSVC++ 5.0 > took 4.38 and 3.28 seconds, a factor of 1.33, and using Gnat 3.15p > on the same machine took 1.38 and 0.85 seconds, a ratio of 1.6 > Clearly, there's something substantially different between our > compilers/hardware/code. I'm using gcc 2.95.2 on a Sunblade 2000. I can't post the code, but it is a pretty standard vector/matrix implementation in C++. Actually, it is designed for very efficient indexing, perhaps at the expense of slightly less efficient construction (it has a pointer for each row of the matrix). That might explain part of the difference you are seeing, but certainly not all. Perhaps your choice of C++ compiler is a factor too.