From: 18k11tm001@sneakemail.com (Russ)
Subject: Re: Is ther any sense in *= and matrices?
Date: 8 Jun 2003 21:24:36 -0700
Date: 2003-06-09T04:24:36+00:00 [thread overview]
Message-ID: <bebbba07.0306082024.7cebb5df@posting.google.com> (raw)
In-Reply-To: AmNEa.67177$d51.133670@sccrnsc01
tmoran@acm.org wrote in message news:<AmNEa.67177$d51.133670@sccrnsc01>...
> >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.
next prev parent reply other threads:[~2003-06-09 4:24 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-06-05 10:45 Is ther any sense in *= and matrices? Preben Randhol
2003-06-05 11:13 ` Vinzent Hoefler
2003-06-05 11:28 ` Preben Randhol
2003-06-05 11:53 ` Vinzent Hoefler
2003-06-05 15:27 ` Preben Randhol
2003-06-05 15:40 ` Vinzent Hoefler
2003-06-05 15:47 ` Preben Randhol
2003-06-05 16:38 ` Vinzent Hoefler
2003-06-05 17:16 ` Preben Randhol
2003-06-05 17:17 ` Preben Randhol
2003-06-05 17:59 ` Vinzent Hoefler
2003-06-07 19:38 ` Russ
2003-06-08 6:46 ` John R. Strohm
2003-06-08 18:51 ` Russ
2003-06-08 20:52 ` tmoran
2003-06-09 4:24 ` Russ [this message]
2003-06-09 5:13 ` John R. Strohm
2003-06-10 9:38 ` Ole-Hjalmar Kristensen
2003-06-10 16:11 ` Wesley Groleau
2003-06-10 19:24 ` Ole Kristensen
2003-06-10 18:33 ` Russ
2003-06-10 23:16 ` John R. Strohm
2003-06-09 6:58 ` tmoran
2003-06-08 22:23 ` John R. Strohm
2003-06-09 6:06 ` Russ
2003-06-09 10:06 ` Mango Jones
2003-06-08 22:56 ` Bobby D. Bryant
2003-06-09 4:27 ` Russ
2003-06-09 5:17 ` John R. Strohm
2003-06-09 14:53 ` Bobby D. Bryant
2003-06-09 17:46 ` Russ
2003-06-10 9:57 ` Ole-Hjalmar Kristensen
2003-06-05 12:33 ` John R. Strohm
2003-06-05 19:25 ` Wesley Groleau
2003-06-05 20:17 ` David C. Hoos
2003-06-05 20:52 ` Wesley Groleau
-- strict thread matches above, loose matches on Subject: below --
2003-06-10 19:00 tmoran
2003-06-10 19:37 ` Ole Kristensen
2003-06-10 19:37 ` Ole Kristensen
2003-06-10 19:48 ` Ole Kristensen
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