       Re: Don't understand behaviour of Solve[]

• To: mathgroup at smc.vnet.net
• Subject: [mg58567] Re: Don't understand behaviour of Solve[]
• From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
• Date: Fri, 8 Jul 2005 00:45:58 -0400 (EDT)
• Organization: Uni Leipzig
• References: <daitlm\$sus\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

say you have s system of equations

x+y==1
x-y==0

if you solve it for y only you get y->1-x and y->x
this is an contradiction because for a general x
this is not true,
while if you solve it for
{x,y} you get the solution {x->1/2,y->1/2}

Regards
Jens

"Oliver Friedrich" <oliver.friedrich at tzm.de>
schrieb im Newsbeitrag
news:daitlm\$sus\$1 at smc.vnet.net...
> Hallo,
>
> I have a problem understanding the general
> behaviour of the Solve[]
> function.
>
> I have a set of equations with the variables
> a,b,c,d and k.
>
> Evaluating Solve[set,k] or Solve[set,{a,b}]
> returns with {}, whereas Solve
> [set,{k,b,c,d}] returns solutions for k,b,c and
> d.
>
> My question: Why does Solve returns no solution
> when searching only for k
> for example and why is there a solution for
> several variables? I thought
> that giving a list of variables just means that
> I want to search for all of
> them. But the procedure doesn't seem to be
> independant from one variable to
> another.
>
> What kind of information contains my list of
> variables except my wish to
> solve for these?
>
> Many thanks
>
> Oliver friedrich
>

```

• Prev by Date: Re: Using InterpolatingFunction from NDSolve
• Next by Date: Re: Mathematica query
• Previous by thread: Re: Don't understand behaviour of Solve[]
• Next by thread: Re: Don't understand behaviour of Solve[]