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Re: Vectors


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 ?


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