Re: Asymptote strangeness...
- To: mathgroup at smc.vnet.net
- Subject: [mg38857] Re: Asymptote strangeness...
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Thu, 16 Jan 2003 03:20:01 -0500 (EST)
- References: <b033br$n11$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Mike,
For x<0
(x + 2)/(Abs[x] - 2)
is
(x + 2)/(-x - 2)
Which is -1 for all x not equal to -2 and is undefined at x = -2.
So there is no asymptote at x=-2, and unless Plot takes a sample height at
x=-2, exactly, in which case it will complain about not getting a real
value, it will be quite unaware of this feature.
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565
"Mike Summers" <mike at miscanthus.net> wrote in message
news:b033br$n11$1 at smc.vnet.net...
> It seems to me that this:
>
> f[x] = (x + 2)/(Abs[x] - 2)
>
>
> should have asymptotes at 2 & -2.
>
> Plot[Evaluate[f[x]], {x, -5, 5}] only shows the asymptote at 2.
>
> Suggestions?
>
> Thanks-- Mike
>
>