RegionPlot of annulus gives a mesh












1












$begingroup$


So I tried plotting an annulus in two ways:



RegionPlot[Annulus[{0,0},{a,b}]]

Graphics[Annulus[{0,0},{a,b}]]


Why does RegionPlot give a fractal looking thing? (see below for when a=1; b=5;)
RegionPlot image



*note, I used wolfram programing lab.






graphics regions







share|improve this question











$endgroup$












  • $begingroup$
    What are $a$ and $b$ here?
    $endgroup$
    – mjw
    10 hours ago










  • $begingroup$
    Try a=1; b=5; But really any values give something weird
    $endgroup$
    – Ion Sme
    10 hours ago






  • 4




    $begingroup$
    Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
    $endgroup$
    – MarcoB
    10 hours ago






  • 1




    $begingroup$
    @IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
    $endgroup$
    – MarcoB
    10 hours ago






  • 2




    $begingroup$
    There are some subtle differences going on how Mma shows Regions and RegionPlot Graphics. Also Regions can be defined analytically via ImplicitRegion or ParametricRegion or as 'flat' MeshRegions. DiscretizeRegion converts every type to a MeshRegion and some functions like RegionPlot might use something similar to DiscretizeRegion under the hood to make plotting easier, whose discretization it for some reason decides to show. Like others wrote you can use ImplicitRegion to get a different (not discretized) look in your case.
    $endgroup$
    – Thies Heidecke
    9 hours ago


















1












$begingroup$


So I tried plotting an annulus in two ways:



RegionPlot[Annulus[{0,0},{a,b}]]

Graphics[Annulus[{0,0},{a,b}]]


Why does RegionPlot give a fractal looking thing? (see below for when a=1; b=5;)
RegionPlot image



*note, I used wolfram programing lab.






graphics regions







share|improve this question











$endgroup$












  • $begingroup$
    What are $a$ and $b$ here?
    $endgroup$
    – mjw
    10 hours ago










  • $begingroup$
    Try a=1; b=5; But really any values give something weird
    $endgroup$
    – Ion Sme
    10 hours ago






  • 4




    $begingroup$
    Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
    $endgroup$
    – MarcoB
    10 hours ago






  • 1




    $begingroup$
    @IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
    $endgroup$
    – MarcoB
    10 hours ago






  • 2




    $begingroup$
    There are some subtle differences going on how Mma shows Regions and RegionPlot Graphics. Also Regions can be defined analytically via ImplicitRegion or ParametricRegion or as 'flat' MeshRegions. DiscretizeRegion converts every type to a MeshRegion and some functions like RegionPlot might use something similar to DiscretizeRegion under the hood to make plotting easier, whose discretization it for some reason decides to show. Like others wrote you can use ImplicitRegion to get a different (not discretized) look in your case.
    $endgroup$
    – Thies Heidecke
    9 hours ago
















1












1








1





$begingroup$


So I tried plotting an annulus in two ways:



RegionPlot[Annulus[{0,0},{a,b}]]

Graphics[Annulus[{0,0},{a,b}]]


Why does RegionPlot give a fractal looking thing? (see below for when a=1; b=5;)
RegionPlot image



*note, I used wolfram programing lab.






graphics regions







share|improve this question











$endgroup$




So I tried plotting an annulus in two ways:



RegionPlot[Annulus[{0,0},{a,b}]]

Graphics[Annulus[{0,0},{a,b}]]


Why does RegionPlot give a fractal looking thing? (see below for when a=1; b=5;)
RegionPlot image



*note, I used wolfram programing lab.






graphics regions




graphics regions






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 9 hours ago









MarcoB

38.1k556114




38.1k556114










asked 10 hours ago









Ion SmeIon Sme

877




877












  • $begingroup$
    What are $a$ and $b$ here?
    $endgroup$
    – mjw
    10 hours ago










  • $begingroup$
    Try a=1; b=5; But really any values give something weird
    $endgroup$
    – Ion Sme
    10 hours ago






  • 4




    $begingroup$
    Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
    $endgroup$
    – MarcoB
    10 hours ago






  • 1




    $begingroup$
    @IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
    $endgroup$
    – MarcoB
    10 hours ago






  • 2




    $begingroup$
    There are some subtle differences going on how Mma shows Regions and RegionPlot Graphics. Also Regions can be defined analytically via ImplicitRegion or ParametricRegion or as 'flat' MeshRegions. DiscretizeRegion converts every type to a MeshRegion and some functions like RegionPlot might use something similar to DiscretizeRegion under the hood to make plotting easier, whose discretization it for some reason decides to show. Like others wrote you can use ImplicitRegion to get a different (not discretized) look in your case.
    $endgroup$
    – Thies Heidecke
    9 hours ago




















  • $begingroup$
    What are $a$ and $b$ here?
    $endgroup$
    – mjw
    10 hours ago










  • $begingroup$
    Try a=1; b=5; But really any values give something weird
    $endgroup$
    – Ion Sme
    10 hours ago






  • 4




    $begingroup$
    Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
    $endgroup$
    – MarcoB
    10 hours ago






  • 1




    $begingroup$
    @IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
    $endgroup$
    – MarcoB
    10 hours ago






  • 2




    $begingroup$
    There are some subtle differences going on how Mma shows Regions and RegionPlot Graphics. Also Regions can be defined analytically via ImplicitRegion or ParametricRegion or as 'flat' MeshRegions. DiscretizeRegion converts every type to a MeshRegion and some functions like RegionPlot might use something similar to DiscretizeRegion under the hood to make plotting easier, whose discretization it for some reason decides to show. Like others wrote you can use ImplicitRegion to get a different (not discretized) look in your case.
    $endgroup$
    – Thies Heidecke
    9 hours ago


















$begingroup$
What are $a$ and $b$ here?
$endgroup$
– mjw
10 hours ago




$begingroup$
What are $a$ and $b$ here?
$endgroup$
– mjw
10 hours ago












$begingroup$
Try a=1; b=5; But really any values give something weird
$endgroup$
– Ion Sme
10 hours ago




$begingroup$
Try a=1; b=5; But really any values give something weird
$endgroup$
– Ion Sme
10 hours ago




4




4




$begingroup$
Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
$endgroup$
– MarcoB
10 hours ago




$begingroup$
Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
$endgroup$
– MarcoB
10 hours ago




1




1




$begingroup$
@IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
$endgroup$
– MarcoB
10 hours ago




$begingroup$
@IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
$endgroup$
– MarcoB
10 hours ago




2




2




$begingroup$
There are some subtle differences going on how Mma shows Regions and RegionPlot Graphics. Also Regions can be defined analytically via ImplicitRegion or ParametricRegion or as 'flat' MeshRegions. DiscretizeRegion converts every type to a MeshRegion and some functions like RegionPlot might use something similar to DiscretizeRegion under the hood to make plotting easier, whose discretization it for some reason decides to show. Like others wrote you can use ImplicitRegion to get a different (not discretized) look in your case.
$endgroup$
– Thies Heidecke
9 hours ago






$begingroup$
There are some subtle differences going on how Mma shows Regions and RegionPlot Graphics. Also Regions can be defined analytically via ImplicitRegion or ParametricRegion or as 'flat' MeshRegions. DiscretizeRegion converts every type to a MeshRegion and some functions like RegionPlot might use something similar to DiscretizeRegion under the hood to make plotting easier, whose discretization it for some reason decides to show. Like others wrote you can use ImplicitRegion to get a different (not discretized) look in your case.
$endgroup$
– Thies Heidecke
9 hours ago












1 Answer
1






active

oldest

votes


















4












$begingroup$

 a = 1; b = 5;


Please try plotting with Region. These look okay to me:



 Region[RegionDifference[Disk[{0, 0}, b], Disk[{0, 0}, a]]]


enter image description here



 Region[Annulus[{0, 0}, {a, b}]]


enter image description here



Here is a decent plot, with RegionPlot:



 RegionPlot[x^2 + y^2 > 1 && x^2 + y^2 < 25, {x, -6, 6}, {y, -6, 6}]


enter image description here



Here it is (again) with Graphics:



 Graphics[{LightBlue, Annulus[{0, 0}, {a, b}]}]


enter image description here






share|improve this answer











$endgroup$













  • $begingroup$
    Hmmm, that worked, but why is RegionPlot so funky?
    $endgroup$
    – Ion Sme
    10 hours ago






  • 1




    $begingroup$
    I think MarcoB mostly answers this below your question. So we can then ask: Why does RegionPlot use one algorithm, and Region another? RegionPlot seems to like functions as inputs, and also likes to have the $x$ and $y$ ranges speciifed ...
    $endgroup$
    – mjw
    10 hours ago












Your Answer





StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "387"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f194211%2fregionplot-of-annulus-gives-a-mesh%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









4












$begingroup$

 a = 1; b = 5;


Please try plotting with Region. These look okay to me:



 Region[RegionDifference[Disk[{0, 0}, b], Disk[{0, 0}, a]]]


enter image description here



 Region[Annulus[{0, 0}, {a, b}]]


enter image description here



Here is a decent plot, with RegionPlot:



 RegionPlot[x^2 + y^2 > 1 && x^2 + y^2 < 25, {x, -6, 6}, {y, -6, 6}]


enter image description here



Here it is (again) with Graphics:



 Graphics[{LightBlue, Annulus[{0, 0}, {a, b}]}]


enter image description here






share|improve this answer











$endgroup$













  • $begingroup$
    Hmmm, that worked, but why is RegionPlot so funky?
    $endgroup$
    – Ion Sme
    10 hours ago






  • 1




    $begingroup$
    I think MarcoB mostly answers this below your question. So we can then ask: Why does RegionPlot use one algorithm, and Region another? RegionPlot seems to like functions as inputs, and also likes to have the $x$ and $y$ ranges speciifed ...
    $endgroup$
    – mjw
    10 hours ago
















4












$begingroup$

 a = 1; b = 5;


Please try plotting with Region. These look okay to me:



 Region[RegionDifference[Disk[{0, 0}, b], Disk[{0, 0}, a]]]


enter image description here



 Region[Annulus[{0, 0}, {a, b}]]


enter image description here



Here is a decent plot, with RegionPlot:



 RegionPlot[x^2 + y^2 > 1 && x^2 + y^2 < 25, {x, -6, 6}, {y, -6, 6}]


enter image description here



Here it is (again) with Graphics:



 Graphics[{LightBlue, Annulus[{0, 0}, {a, b}]}]


enter image description here






share|improve this answer











$endgroup$













  • $begingroup$
    Hmmm, that worked, but why is RegionPlot so funky?
    $endgroup$
    – Ion Sme
    10 hours ago






  • 1




    $begingroup$
    I think MarcoB mostly answers this below your question. So we can then ask: Why does RegionPlot use one algorithm, and Region another? RegionPlot seems to like functions as inputs, and also likes to have the $x$ and $y$ ranges speciifed ...
    $endgroup$
    – mjw
    10 hours ago














4












4








4





$begingroup$

 a = 1; b = 5;


Please try plotting with Region. These look okay to me:



 Region[RegionDifference[Disk[{0, 0}, b], Disk[{0, 0}, a]]]


enter image description here



 Region[Annulus[{0, 0}, {a, b}]]


enter image description here



Here is a decent plot, with RegionPlot:



 RegionPlot[x^2 + y^2 > 1 && x^2 + y^2 < 25, {x, -6, 6}, {y, -6, 6}]


enter image description here



Here it is (again) with Graphics:



 Graphics[{LightBlue, Annulus[{0, 0}, {a, b}]}]


enter image description here






share|improve this answer











$endgroup$



 a = 1; b = 5;


Please try plotting with Region. These look okay to me:



 Region[RegionDifference[Disk[{0, 0}, b], Disk[{0, 0}, a]]]


enter image description here



 Region[Annulus[{0, 0}, {a, b}]]


enter image description here



Here is a decent plot, with RegionPlot:



 RegionPlot[x^2 + y^2 > 1 && x^2 + y^2 < 25, {x, -6, 6}, {y, -6, 6}]


enter image description here



Here it is (again) with Graphics:



 Graphics[{LightBlue, Annulus[{0, 0}, {a, b}]}]


enter image description here







share|improve this answer














share|improve this answer



share|improve this answer








edited 10 hours ago

























answered 10 hours ago









mjwmjw

1,17610




1,17610












  • $begingroup$
    Hmmm, that worked, but why is RegionPlot so funky?
    $endgroup$
    – Ion Sme
    10 hours ago






  • 1




    $begingroup$
    I think MarcoB mostly answers this below your question. So we can then ask: Why does RegionPlot use one algorithm, and Region another? RegionPlot seems to like functions as inputs, and also likes to have the $x$ and $y$ ranges speciifed ...
    $endgroup$
    – mjw
    10 hours ago


















  • $begingroup$
    Hmmm, that worked, but why is RegionPlot so funky?
    $endgroup$
    – Ion Sme
    10 hours ago






  • 1




    $begingroup$
    I think MarcoB mostly answers this below your question. So we can then ask: Why does RegionPlot use one algorithm, and Region another? RegionPlot seems to like functions as inputs, and also likes to have the $x$ and $y$ ranges speciifed ...
    $endgroup$
    – mjw
    10 hours ago
















$begingroup$
Hmmm, that worked, but why is RegionPlot so funky?
$endgroup$
– Ion Sme
10 hours ago




$begingroup$
Hmmm, that worked, but why is RegionPlot so funky?
$endgroup$
– Ion Sme
10 hours ago




1




1




$begingroup$
I think MarcoB mostly answers this below your question. So we can then ask: Why does RegionPlot use one algorithm, and Region another? RegionPlot seems to like functions as inputs, and also likes to have the $x$ and $y$ ranges speciifed ...
$endgroup$
– mjw
10 hours ago




$begingroup$
I think MarcoB mostly answers this below your question. So we can then ask: Why does RegionPlot use one algorithm, and Region another? RegionPlot seems to like functions as inputs, and also likes to have the $x$ and $y$ ranges speciifed ...
$endgroup$
– mjw
10 hours ago


















draft saved

draft discarded




















































Thanks for contributing an answer to Mathematica Stack Exchange!


  • Please be sure to answer the question. Provide details and share your research!

But avoid …



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


Use MathJax to format equations. MathJax reference.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f194211%2fregionplot-of-annulus-gives-a-mesh%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







-

Popular posts from this blog

How to make a Squid Proxy server?

Image
1 I want to set up squid proxy server for monitoring user activity in a network and Internet Web URL filtering for user. I also want to configure the user login, user log, user access group, and block unwanted web sites in my network. Please help me and guide me the full process to do this. server proxy squid share | improve this question edited Jul 31 '12 at 14:45 Jorge Castro 37.1k 107 422 617 asked Jul 31 '12 at 5:16 Goivind Tiwari Goivind Tiwari ...
Read more

Is this a new Fibonacci Identity?

Image
6 1 $begingroup$ I have found the following Fibonacci Identity (and proved it). If $F_n$ denotes the nth Fibonacci Number, we have the following identity begin{equation} F_{n-r+h}F_{n+k+g+1} - F_{n-r+g}F_{n+k+h+1} = (-1)^{n+r+h+1} F_{g-h}F_{k+r+1} end{equation} where $F_1 = F_2 = 1$ , $r leq n$ , $h leq g$ , and $n, g, k in mathbb{N}$ . It is not too hard to show that this identity subsumes Cassini's Identity, Catalan's Identity, Vajda's Idenity, and d'Ocagne's identity to name a few. I have done a pretty thorough literature review, and I have not found anything like this, but I am still wondering if anyone has seen this identity before? I found this by accident after noticing some patterns in some analysis work I was doing, so if this is already known I would be curious to see w...
Read more

19世紀

Image
この記事は検証可能な参考文献や出典が全く示されていないか、不十分です。 出典を追加して記事の信頼性向上にご協力ください。 （ 2012年3月 ） 千年紀: 2千年紀 世紀: 18世紀 - 19世紀 - 20世紀 十年紀: 1800年代 1810年代 1820年代 1830年代 1840年代 1850年代 1860年代 1870年代 1880年代 1890年代 19世紀に君臨した大英帝国。 19世紀 （じゅうきゅうせいき）は、西暦1801年から西暦1900年までの100年間を指す世紀。 目次 1 19世紀の歴史 1.1 国民国家の成立 1.2 帝国主義の興隆 1.3 列強の植民地争奪戦 2 できごと 2.1 1800年代 2.2 1810年代 2.3 1820年代 2.4 1830年代 2.5 1840年代 2.6 1850年代 2.7 1860年代 2.8 1870年代 2.9 1880年代 2.10 1890年代 2.11 1900年代 3 文化 3.1 文学 3.2 音楽 3.3 思想 3.4 科学 3.5 技術 4 人物 4.1 ヨーロッパ 4.1.1 政治家・王族 4.1.1.1 フランス 4.1.1.2 オーストリア＝ハンガリー 4.1.1.3 ロシア 4.1.1.4 イギリス 4.1.1.5 ドイツ（プロイセンほかドイツ領邦を含む） 4.1.1.6 北欧 4.1.1.7 イタリア 4.1.1.8 スペイン 4.1.1.9 ベルギー 4.1.1.10 ギリシア 4.1.2 軍人 4.1.3 実業家 4.1.4 科学と技術 4.1.5 思想と哲学・人文諸学 4.1.6 宗教 4.1.7 文学 4.1.8 美術 4.1.9 音楽 4.1.10 社会事業家 4.1.11 探検家・旅行家 4.1.12 料...
Read more