From: "Bobby D. Bryant" <bdbryant@mail.utexas.edu>
Subject: Re: Is ther any sense in *= and matrices?
Date: Mon, 09 Jun 2003 08:53:17 -0600
Date: 2003-06-09T08:53:17-06:00 [thread overview]
Message-ID: <pan.2003.06.09.14.53.15.912223@mail.utexas.edu> (raw)
In-Reply-To: bebbba07.0306082027.2c50eb6b@posting.google.com
On Sun, 08 Jun 2003 21:27:13 -0700, Russ wrote:
> "Bobby D. Bryant" <bdbryant@mail.utexas.edu> wrote in message
> news:<pan.2003.06.08.22.56.37.297066@mail.utexas.edu>...
>> On Sun, 08 Jun 2003 11:51:31 -0700, Russ wrote:
>>
>> > "John R. Strohm" <strohm@airmail.net> wrote in message
>> > news:<bbumef$fnq@library2.airnews.net>...
>>
>> >> With all due respect, ladies and gentlemen, it has been known for a
>> >> very long time that the difference in "efficiency" between A := A +
>> >> B and A += B is lost in the noise floor compared to the improvements
>> >> that can be gotten by improving the algorithms involved.
>> >
>> > 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
>> > just shy of a factor of 3, folks. If that's your "noise floor," I
>> > can't help wonder what kind of "algorithms" you are dealing with!
>>
>> I'm just curious why the compiler didn't generate the same code for
>> both versions.
>
> The compiler didn't generate the code. I did.
No, I'm talking about the compiler's machine-code output. You wrote in
C++, right?
--
Bobby Bryant
Austin, Texas
next prev parent reply other threads:[~2003-06-09 14:53 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
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 [this message]
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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