Re: Vectors
- To: mathgroup at smc.vnet.net
- Subject: [mg13921] Re: [mg13894] Vectors
- From: BobHanlon at aol.com
- Date: Mon, 7 Sep 1998 01:22:47 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Olivier,
Check your input.
Bob Hanlon
_______________
A = {a1, a2, a3}; B = {b1, b2, b3};
Cross[A, B]
{a2 b3-a3 b2,a3 b1-a1 b3,a1 b2-a2 b1}
Cross[A, B] == -Cross[B, A]
True
Cross[A, A]
{0,0,0}
In a message dated 9/6/98 6:59:57 AM, ogeorg at imtsg12.epfl.ch wrote:
>I want to do symbolic calculation with vectors, in particular, I want to
>do a vector product. But if I declare:
>
> A = (a b c)
>
>and do
>
> A x A
>
>(which should give zero), but instead I get:
>
> Cross::"nonn1": "Not all of the arguments are vectors
> of required length
>
>since there's no way for mathematica to know that a, b and c represent
>numerical value and not functions or lists. Is there a way around to
>perform this kind of calculation ?