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 ?