From: 18k11tm001@sneakemail.com (Russ)
Subject: Re: Is ther any sense in *= and matrices?
Date: 7 Jun 2003 12:38:40 -0700
Date: 2003-06-07T19:38:41+00:00 [thread overview]
Message-ID: <bebbba07.0306071138.6bf9784f@posting.google.com> (raw)
In-Reply-To: slrnbdupg6.88r.randhol+abuse@kiuk0152.chembio.ntnu.no
Preben Randhol <randhol+abuse@pvv.org> wrote in message news:<slrnbdupg6.88r.randhol+abuse@kiuk0152.chembio.ntnu.no>...
> Vinzent Hoefler wrote:
> > Preben Randhol wrote:
> >
> >>Vinzent Hoefler wrote:
> >>> Of course it is. But because you have to write the Multiply function
> >>> yourself anyway and such can take care of that issue, I don't see why
> >>> this should be a problem.
> >>
> >>Because it doesn't make sense mathematically.
> >
> > Dividing by zero doesn't make sense either. So IMO that's what the
> > Constraint_Error is for.
>
> The Contraint_Error here is for that *= would return a C (m x n) which
> differes from the A (n x n). So *= is only usefule (/= too) in special
> cases such as square matrix. Therefore you must make a function Prod
> (A,B) at any rate and the *= will be of no use as Prod (A,B) is
> general.
"*=" is not so useful for multipying non-square matrices. However, it
is very useful for multiplying a matrix (or a vector) by a scalar. For
example,
A *= 2.0
can be used to multiply matrix A by two in place. This is potentially
more efficient than A := A * 2 for all the same reasons discussed with
respect to "+=".
next prev parent reply other threads:[~2003-06-07 19:38 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 [this message]
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
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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