wrong limit



On Qua, 2008-12-31 at 13:53 +0100, Michel Gosse wrote:
> With maxima 5.14 :
> 
> limit((7-x)*exp(x-4),x,inf)
> inf
> 
> I think i must obtain minf ?

You're right, and Maxima 5.16 is also right:

Maxima 5.16post http://maxima.sourceforge.net
Using Lisp SBCL 1.0.11.debian
(%i1) limit((7-x)*exp(x-4),x,inf);
(%o1)                       minf

By the way, this example puzzles me because the function is clearly
negative for x>7, so the limit must be minf, but it can also be written
as:
limit((7-x)/exp(4-x),x,inf)
and applying L'Hopytal's rule:
limit(1/exp(4-x),x,inf)
which is inf. What's wrong with this?

Regards,
Jaime