Re: Re: Graphing Abnormalities of Functions

• To: mathgroup at smc.vnet.net
• Subject: [mg29555] Re: [mg29552] Re: Graphing Abnormalities of Functions
• From: BobHanlon at aol.com
• Date: Sun, 24 Jun 2001 22:10:13 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```In a message dated 2001/6/24 2:04:00 AM, rrosario11 at my-deja.com writes:

>By a hole, I mean a removable discontinuity in a graph. For example,
>the function ((x^2) + x - 2)/(x - 1) is discontinuous because when
>x=1, the function is undefined. I learned that this is called a
>"hole." Perhaps I am using the wrong terminology. If so, silly me LOL
>:-)
>
>In textbooks, this discontinuity is indicated by displaying a hollow
>circle at the point of discontinuity (hole).
>
>Is there a way to tell Mathematica to draw this circle at the point of
>discontinuity rather than simply display a break in the graph?
>

Needs["Graphics`Graphics`"];
Needs["Graphics`Colors`"];

There is no break in the graph for the example that you provided.

(x^2+x-2)/(x-1)//Cancel

x + 2

f[x_] := (x^2+7x-2)/(x-1);

DisplayTogether[
Plot[{f[x], x+7}, {x, -19, 1},
PlotStyle -> {Blue,
{AbsoluteDashing[{8, 8}], Magenta}},
Epilog ->
{Text[StyleForm["o",
FontSize -> 18, FontColor -> Red,
FontWeight -> "Bold"],
{1, 0}],
Text[StyleForm[ToString[
FontSize -> 14],
{-10, 15}]}],
Plot[{f[x], x+7}, {x, 1, 21},
PlotStyle -> {Blue,
{AbsoluteDashing[{8, 8}], Magenta}}],
PlotRange -> {All, {-13, 31}},
ImageSize -> 400];

Bob Hanlon
Chantilly, VA  USA

```

• Prev by Date: RE: Re: Graphing Abnormalities of Functions
• Next by Date: How do I really get rid of previous results?
• Previous by thread: RE: Re: Graphing Abnormalities of Functions
• Next by thread: RE: Re: Graphing Abnormalities of Functions