Plot2d bugs 694770 and 710677



--- Raymond Toy <toy@rtp.ericsson.se> wrote:

> Heh!  That was exactly the function I used when trying out some of
> the adaptive plotting changes.  In any case, I don't think we can
ever 
> be smart enough to plot this carefully because we can't if the 
> interval truly contains 0.
> 
> And plotting implicitly starts from a fixed number of samples, so we
> could potentially miss poles if the pole is narrow enough and the
> sampling coarse enough.  Don't think we could ever be smart enough to
> find a pole like that.

I don't know much about that (does any CAS have pole finding routines?)
but that problem reminds me of a silly question I've been wanting to
ask:

in the case of something like:

                        (x + 2) (x + 1)                            
                        ---------------
                             x + 1

Maxima will simplify this to x+2.  But, as written, doesn't this
expression have a hole at x=-1?  It will do the x+2 thing everywhere
else - is it OK to simplify because it's a case of zero over zero?  I
thought that didn't evaluate to one mathematically.

I'm assuming I'm just a dork, but can someone set me straight?

CY


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