* Richard Fateman <fateman at cs.berkeley.edu> [2007-09-23 21:47:51 -0700]:
> It can't solve for x in x*log(x)=u.
> Can you?
> RJF
Of course not, but the substitution can be worked out without solving
for x. I actually looked up the source code for changevar, and got the
impression already that the problem is in Maxima's trying to solve for
x. Thank you for confirming my guess.
Milan
>
> > -----Original Message-----
> > From: maxima-bounces at math.utexas.edu
> > [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Milan Lukic
> > Sent: Sunday, September 23, 2007 9:21 PM
> > To: maxima at math.utexas.edu
> > Subject: Changevar
> >
> > It seems (to me) that Maxima is unable to perform the change of
> > variable x*log(x)=u in the integral of
> > (log(x)+1)*sqrt(1+(x*log(x))^2). Namely,
> >
> > (%i3) A : 'integrate((log(x)+1)*sqrt(1+(x*log(x))^2),x);
> > (%i4) changevar(A,x*log(x)-u,u,x);
> >
> > returns the original integral. BTW, it can't find the antiderivative
> > either.
> >
> > Milan
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