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Re: Integrate and warning messages.

• To: mathgroup at smc.vnet.net
• Subject: [mg35304] Re: [mg35295] Integrate and warning messages.
• From: Andrzej Kozlowski <andrzej at platon.c.u-tokyo.ac.jp>
• Date: Mon, 8 Jul 2002 03:15:31 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

Take your equation and to see things better replace Sqrt[1+3x^2] by a 
symbols, say a:

In[5]:=
-Sqrt[1+3x^2]/(1+Sqrt[1+3x^2]) +
Log[Exp[Sqrt[1+3x^2]]] - Sqrt[1+3x^2]Log[Exp[Sqrt[1+3x^2]]]/(1+Sqrt[
1+3x^2]) == 0/.Sqrt[1+3x^2]->a

Out[5]=
-(a/(1 + a)) + Log[E^a] - (a*Log[E^a])/(1 + a) == 0

In[6]:=
FullSimplify[%]

Out[6]=
(-a + Log[E^a])/(1 + a) == 0

This reduces to Log[E^a]==a. This equation holds in a part of the 
complex plane (including the real line) and is not valid elsewhere (e.g. 
for a = 2Pi I). Not surprisingly Mathematica cannot combine this 
information with the rest of your equations.

Andrzej Kozlowski
Toyama International University
JAPAN
http://platon.c.u-tokyo.ac.jp/andrzej/

On Saturday, July 6, 2002, at 06:46  PM, Andrea wrote:

> Hi,
> I'm trying to solve an integral and before getting the result
> Mathematica warns me several times with this message:
>
> Solve::incnst: Inconsistent or redundant transcendental equation.
>
> After reduction, the bad equation is -Sqrt[1+3x^2]/(1+Sqrt[1+3x^2]) +
> Log[Exp[Sqrt[1+3x^2]]] - Sqrt[1+3x^2]Log[Exp[Sqrt[1+3x^2]]]/(1+Sqrt[
> 1+3x^2]) == 0
>
>
> Can anyone explain it to me??
>
> Thanks in advance,
> Andrea.
>
>
>