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I type the following code in Mathematica 11:

For[n = 1, n <= 3, n++,
 RegionPlot[x^2 + y^3 < n, {x, -2, 2}, {y, -2, 2}]
]

Then I press Shift+Enter, but Mathematica does not output any figures. Where is the problem? Thanks in advance.

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    $\begingroup$ This is a common mistake for users new to Mathematica, or coming from earlier versions. Plots return Graphics expressions rather than displaying them as side-effects. See (47123). You could add Print but generally a better method is to replace For with Table: Table[RegionPlot[x^2 + y^3 < n, {x, -2, 2}, {y, -2, 2}], {n, 1, 3}]. You can further format that output with Column or GraphicsColumn as desired, or animate it with ListAnimate. $\endgroup$
    – Mr.Wizard
    Aug 16, 2016 at 8:24
  • $\begingroup$ Note: does there exist a canonical Q&A on this issue? If not I think a post should be made in (18393) regarding this, as it has come up quite often. $\endgroup$
    – Mr.Wizard
    Aug 16, 2016 at 8:28
  • $\begingroup$ Mr.Wizard: Thank you for your comment. $\endgroup$ Aug 16, 2016 at 8:31

2 Answers 2

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It depends on what your aim. If it is just to 'print' 3 graphics:

For[n = 1, n <= 3, n++, 
 Print@RegionPlot[x^2 + y^3 < n, {x, -2, 2}, {y, -2, 2}]]

If you want an object you can use and refer to:

f[x_, y_] := x^2 + y^3
rps=RegionPlot[f[x, y] < #, {x, -2, 2}, {y, -2, 2}] & /@ Range[3]

This is also a useful link with respect to loops in Mathematica.

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  • $\begingroup$ ubpdqn: Thank you for your answer. $\endgroup$ Aug 16, 2016 at 8:32
  • $\begingroup$ @Wei-ChengLiu you're welcome. I had exactly the same question when I first started using Mma. Have fun:) $\endgroup$
    – ubpdqn
    Aug 16, 2016 at 8:34
  • $\begingroup$ Surely in this case Table[]>For[] $\endgroup$
    – Feyre
    Aug 16, 2016 at 9:53
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    $\begingroup$ @Feyre as you and Mr.Wizard have suggested Table may be natural alternative. I provided link to motivate looking at alternatives. $\endgroup$
    – ubpdqn
    Aug 16, 2016 at 9:57
  • $\begingroup$ @Feyre & ubpdqn Thank you for your comments. $\endgroup$ Aug 16, 2016 at 11:53
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For fun

Example

Manipulate[
 RegionPlot[x^2 + y^3 < n, {x, -2, 2}, {y, -2, 2}],
 {n, 1, 3, 1}
 ]
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  • $\begingroup$ e.doroskevic: Thank you for your answer. $\endgroup$ Aug 16, 2016 at 8:32
  • $\begingroup$ @Wei-ChengLiu you are most welcome $\endgroup$ Aug 16, 2016 at 8:34

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