Re: Solve bug !!
- To: mathgroup at smc.vnet.net
- Subject: [mg31211] Re: Solve bug !!
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Fri, 19 Oct 2001 03:12:01 -0400 (EDT)
- Organization: Universitaet Leipzig
- References: <9qjjlh$j84$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
why we *must* obtain a minus sign ?
In[]:=
eqn = (E^(-c))^2 - A*E^(-c) + 1 == 0;
sol = Solve[eqn, c];
sol = Solve[eqn, c]
Out[]={True,True}
especial if you get a message like
Solve::"ifun": "Inverse functions are being used by \!\(Solve\), so some
\
solutions may not be found."
Regards
Jens
Marcel wrote:
>
> Where is the minus sign whe must obtain in the second case??
>
> > Solve[(E^c)^2 - A*E^c + 1 == 0, c]
>
> {{c -> Log[(1/2)*(A - Sqrt[-4 + A^2])]},
> {c -> Log[(1/2)*(A + Sqrt[-4 + A^2])]}}
>
> > Solve[(E^(-c))^2 - A*E^(-c) + 1 == 0, c]
>
> {{c -> Log[(1/2)*(A - Sqrt[-4 + A^2])]},
> {c -> Log[(1/2)*(A + Sqrt[-4 + A^2])]}}
>
> Mathematica 4.1, Windows 2000 SP2, PII400.
>
> Marcel Aguilella