MATLAB Central Newsreader - cross product and mat lab

cross product and mat lab

Rufus Worrell — Wed, 06 Feb 2008 13:07:10 -0500

Hey guys I was wondering I have 3 vectors: a, b, c. now
finding the cross product of them on paper is straight
forward but how would mat lab do a x b .c and a.b x c if a =
(1,2,3), b = (4,5,6) and c = (7,8,9)

Thanks!

Re: cross product and mat lab

Rune Allnor — Wed, 06 Feb 2008 13:09:19 -0500

On 6 Feb, 14:07, "Rufus Worrell" <hollywoodba...@AOL.com> wrote:
> Hey guys I was wondering I have 3 vectors: a, b, c. =A0now
> finding the cross product of them on paper is straight
> forward but how would mat lab do a x b .c and a.b x c if a =3D
> (1,2,3), b =3D (4,5,6) and c =3D (7,8,9)
>
> Thanks!

help cross
help dot

Rune

Re: cross product and mat lab

Yumnam Kirani Singh — Wed, 06 Feb 2008 14:12:38 -0500

see help on cross and dot! I hope, you will easily solve your problem, if you think a little deeper.

Re: cross product and mat lab

Thomas Pieper — Wed, 06 Feb 2008 15:20:04 -0500

Re: cross product and mat lab

Roger Stafford — Wed, 06 Feb 2008 16:17:02 -0500

"Rufus Worrell" <hollywoodbatez@AOL.com> wrote in message <focbdu$hvp
$1@fred.mathworks.com>...
> Hey guys I was wondering I have 3 vectors: a, b, c. now
> finding the cross product of them on paper is straight
> forward but how would mat lab do a x b .c and a.b x c if a =
> (1,2,3), b = (4,5,6) and c = (7,8,9)
>
> Thanks!
----------
The quantities

(a x b) . c
(b x c) . a
(c x a) . b
a . (b x c)
b . (c x a)
c . (a x b)

all give the same value and they can all be evaluated as

det([a;b;c])

In your particular example the answer will be zero because a, b, and c are
linearly dependent, which is to say that they are coplanar. There is zero
volume in the parallelepiped formed by them.

Roger Stafford