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Is it possible to plot a function over a interval with a gap in the middle; e.g., $f(x)=x^2$ over $-5<x<-1\cup1<x<5$?

I am using Mathematica 7 and most of the options in the answers don't seem to work for me.

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4 Answers 4

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In V8 and up, one can use ConditionalExpression:

Plot[ConditionalExpression[x^2, -5 < x < -1 || 1 < x < 5], {x, -5, 5}]

Mathematica graphics


Response to updated question

This might work in all versions of Mathematica:

Show[
 Plot[x^2, {x, -5, -1}],
 Plot[x^2, {x, 1, 5}],
 PlotRange -> All]
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  • $\begingroup$ Piecewise[] with Indeterminate as the default case works here as well. $\endgroup$ Dec 9, 2016 at 21:11
  • $\begingroup$ @J.M. Nice to hear from you, again! $\endgroup$
    – Michael E2
    Dec 9, 2016 at 22:45
  • $\begingroup$ It's nice to be around again, for sure. :) I was ill for most of my hiatus... $\endgroup$ Dec 9, 2016 at 22:48
  • $\begingroup$ @J.M. I'm sorry to hear that. I wish you better health in the coming year! $\endgroup$
    – Michael E2
    Dec 9, 2016 at 22:49
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You can also define f conditionally:

f[x_] := x^2 /; (-5 < x < -1 || 1 < x < 5)
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    $\begingroup$ This is good, but f[x_ /; (-5 < x < -1 || 1 < x < 5)] := x^2 is better $\endgroup$
    – m_goldberg
    Nov 20, 2016 at 22:22
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+100
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With

reg = ImplicitRegion[-5 < x < -1 || 1 < x < 5, x]

or

reg = Interval[{-5, -1}, {1, 5}]

do

Plot[x^2, {x} ∈ reg]

enter image description here


EDIT

This might work for v7:

Plot[If[-5 < x < -1 || 1 < x < 5, x^2], {x, -5, 5}]
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  • $\begingroup$ I am using Mathematica 7 and these options don't seem to work. $\endgroup$
    – gbd
    Nov 20, 2016 at 22:17
  • $\begingroup$ This is a nice V10+ solution to the problem: +50 just to draw attention to it for future users with an up-to-date Mathematica. Plot[x^2, {x} ∈ Interval[{-5, -1}, {1, 5}]] seems particularly nice to code. $\endgroup$
    – Michael E2
    Nov 20, 2016 at 22:48
  • $\begingroup$ @MichaelE2 Thanks for the kind words :) $\endgroup$
    – corey979
    Nov 20, 2016 at 23:03
  • $\begingroup$ Hmm, when I started the bounty, the least award on the popup menu was 100. Well, I've seen +50 bounties, so I probably messed up somehow. But what the heck, think of it as a holiday bonus. Don't spend it all in one place. :) -- As I said, I like the fact that one just specifies the desired domain, and you don't have to define a new, temporary, auxiliary function or other such nonsense. $\endgroup$
    – Michael E2
    Nov 26, 2016 at 19:28
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Another way is with the option RegionFunction:

Plot[x^2, {x, -5, 5}, RegionFunction -> Function[x, -5 < x < -1 || 1 < x < 5]]

enter image description here

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    $\begingroup$ I guess this should work in V6 and higher. $\endgroup$
    – Michael E2
    Nov 21, 2016 at 2:20

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