Re: [Maxima-bugs] [ maxima-Bugs-1281737 ] limit(atan(x)/(1/exp(1)-exp(-(1+x)^2)),x,inf,plus) - wrong



>>>>> "Raymond" == Raymond Toy  writes:

>>>>> ">" == SourceForge net  writes:
    >>> Bugs item #1281737, was opened at 2005-09-04 15:30

    Raymond> [snip]
    >>> Summary: limit(atan(x)/(1/exp(1)-exp(-(1+x)^2)),x,inf,plus) - wrong

[snip]

While looking for other stuff, I notice that this exact limit problem
was discussed at the beginning of this year.  See the thread
http://www.math.utexas.edu/pipermail/maxima/2005/009063.html

There's even the same analysis of the issue with log(-1-%i*x) from
Barton.  Stavros also mentions some bugs with the limit of atan2,
reported as bug 1103515.  From the code, I see that atan2 gets the
limits correctly only by chance because it computes limit(atan2) =
atan(limit), so my fix for the log issue is correct only by chance
too.

    Raymond> With this fix we get the expected limits for the original bug report,
    Raymond> and the two simplified cases.  All of the tests pass, but that's
    Raymond> hardly conclusive.

I'm going to apply this patch because it does fix the issue with log
(with a pointer to the MIT TR where many (most) of the ideas for limit
come from).

Now I just have to figure out how to make atan2 work.  This seems
significantly harder than log because atan2 takes 2 args, so extra
care is needed.

Ray