Re: Strange empty set of solutions

• To: mathgroup at smc.vnet.net
• Subject: [mg71793] Re: Strange empty set of solutions
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Wed, 29 Nov 2006 02:56:35 -0500 (EST)
• Organization: Uni Leipzig
• References: <ekh7pg\$sgs\$1@smc.vnet.net>

```Hi,

and we can't read you mind and the memory of your computer
so we must imagine a matrix M and write down

Solve[{{{1, 2, 3}, {2, 4, 6}, {1, -10, 0}}.{a, b, c} == {0, 0, 0},
a^2 + b^2 + c^2 == 1}, {a, b, c}]

and got two solutions ...

Regards
Jens

José Carlos Santos wrote:
> Hi all,
>
> I have a certain 3 x 3 numerical matrix M. If I type
>
> Solve[M.{a,b,c}=={0,0,0},{a,b,c}]
>
> I get
>
> {{a -> 0. + 0.0410026 c, b -> 0. + 1.35294 c}}
>
> However, if I type
>
> Solve[{M.{a,b,c}=={0,0,0},a^2+b^2+c^2==1},{a,b,c}]
>
> I get the empty set. Why is that? I should get two solutions!
>
> Best regards,
>
> Jose Carlos Santos
>

```

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