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
    Mar 29 at 20:03










  • $begingroup$
    Try a=1; b=5; But really any values give something weird
    $endgroup$
    – Ion Sme
    Mar 29 at 20:08






  • 4




    $begingroup$
    Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
    $endgroup$
    – MarcoB
    Mar 29 at 20:12






  • 1




    $begingroup$
    @IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
    $endgroup$
    – MarcoB
    Mar 29 at 20:17






  • 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
    Mar 29 at 21:19


















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
    Mar 29 at 20:03










  • $begingroup$
    Try a=1; b=5; But really any values give something weird
    $endgroup$
    – Ion Sme
    Mar 29 at 20:08






  • 4




    $begingroup$
    Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
    $endgroup$
    – MarcoB
    Mar 29 at 20:12






  • 1




    $begingroup$
    @IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
    $endgroup$
    – MarcoB
    Mar 29 at 20:17






  • 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
    Mar 29 at 21:19
















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 Mar 29 at 20:48









MarcoB

38.5k557115




38.5k557115










asked Mar 29 at 20:00









Ion SmeIon Sme

877




877












  • $begingroup$
    What are $a$ and $b$ here?
    $endgroup$
    – mjw
    Mar 29 at 20:03










  • $begingroup$
    Try a=1; b=5; But really any values give something weird
    $endgroup$
    – Ion Sme
    Mar 29 at 20:08






  • 4




    $begingroup$
    Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
    $endgroup$
    – MarcoB
    Mar 29 at 20:12






  • 1




    $begingroup$
    @IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
    $endgroup$
    – MarcoB
    Mar 29 at 20:17






  • 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
    Mar 29 at 21:19




















  • $begingroup$
    What are $a$ and $b$ here?
    $endgroup$
    – mjw
    Mar 29 at 20:03










  • $begingroup$
    Try a=1; b=5; But really any values give something weird
    $endgroup$
    – Ion Sme
    Mar 29 at 20:08






  • 4




    $begingroup$
    Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
    $endgroup$
    – MarcoB
    Mar 29 at 20:12






  • 1




    $begingroup$
    @IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
    $endgroup$
    – MarcoB
    Mar 29 at 20:17






  • 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
    Mar 29 at 21:19


















$begingroup$
What are $a$ and $b$ here?
$endgroup$
– mjw
Mar 29 at 20:03




$begingroup$
What are $a$ and $b$ here?
$endgroup$
– mjw
Mar 29 at 20:03












$begingroup$
Try a=1; b=5; But really any values give something weird
$endgroup$
– Ion Sme
Mar 29 at 20:08




$begingroup$
Try a=1; b=5; But really any values give something weird
$endgroup$
– Ion Sme
Mar 29 at 20:08




4




4




$begingroup$
Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
$endgroup$
– MarcoB
Mar 29 at 20:12




$begingroup$
Because it discretized the region in order to plot it, and it is showing the underlying triangulation mesh.
$endgroup$
– MarcoB
Mar 29 at 20:12




1




1




$begingroup$
@IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
$endgroup$
– MarcoB
Mar 29 at 20:17




$begingroup$
@IonSme I guess they just use different defaults for plotting; the Graphics result is "normal-looking" though.
$endgroup$
– MarcoB
Mar 29 at 20:17




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
Mar 29 at 21:19






$begingroup$
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
Mar 29 at 21:19












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
    Mar 29 at 20:13






  • 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
    Mar 29 at 20:17












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
    Mar 29 at 20:13






  • 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
    Mar 29 at 20:17
















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
    Mar 29 at 20:13






  • 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
    Mar 29 at 20:17














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 Mar 29 at 20:26

























answered Mar 29 at 20:07









mjwmjw

1,26810




1,26810












  • $begingroup$
    Hmmm, that worked, but why is RegionPlot so funky?
    $endgroup$
    – Ion Sme
    Mar 29 at 20:13






  • 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
    Mar 29 at 20:17


















  • $begingroup$
    Hmmm, that worked, but why is RegionPlot so funky?
    $endgroup$
    – Ion Sme
    Mar 29 at 20:13






  • 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
    Mar 29 at 20:17
















$begingroup$
Hmmm, that worked, but why is RegionPlot so funky?
$endgroup$
– Ion Sme
Mar 29 at 20:13




$begingroup$
Hmmm, that worked, but why is RegionPlot so funky?
$endgroup$
– Ion Sme
Mar 29 at 20:13




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
Mar 29 at 20:17




$begingroup$
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
Mar 29 at 20:17


















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

Plaza Victoria

Image
Plaza Victoria Plaza Victoria en 2017 Otros nombres Plaza de La Victoria Localización El Almendral, Valparaíso, Chile Vías adyacentes Chacabuco, Molina, Plaza Victoria y Edwards Creación 1841 Metro Bellavista Ubicación 33°02′46″S 71°37′11″O  /  -33.04624167, -71.61980833 Coordenadas: 33°02′46″S 71°37′11″O  /  -33.04624167, -71.61980833 [editar datos en Wikidata] La Plaza Victoria , también llamada Plaza de la Victoria , [ 1 ] ​ es una plaza ubicada en el sector El Almendral del plan de la ciudad de Valparaíso, Chile, de importancia patrimonial, que incluye valiosas estatuas y especies vegetales. [ 2 ] ​ La plaza se creó como tal en la primera mitad del siglo XIX, tomando previamente los nombres de Plaza Nueva y Plaza de Orrego . Si bien desde sus inicios tuvo relevancia histórica, no fue sino a partir de fines de los años 1860 cuando comenzó a cobrar mayor importancia y se convirtió en uno de los principales centros sociales de l...
Read more

Puebla de Zaragoza

Image
Para otros usos de este término, véase Puebla (desambiguación). Heroica Puebla de Zaragoza Localidad De arriba a abajo de izquierda a derecha: Estrella de Puebla, Volcán Popocatépetl, Catedral de Puebla, Monumento a Ignacio Zaragoza, Estadio Cuauhtémoc, Angelópolis y Vista panorámica de la ciudad. Escudo Otros nombres: El relicario de América/ La ciudad de los Ángeles/ La Angelópolis Lema: Muy noble y muy leal ciudad de Puebla de los Ángeles Heroica Puebla de Zaragoza Localización de Heroica Puebla de Zaragoza en México Heroica Puebla de Zaragoza Localización de Heroica Puebla de Zaragoza en Puebla Mapa interactivo Coordenadas 19°03′05″N 98°13′04″O  /  19.051388888889, -98.217777777778 Coordenadas: 19°03′05″N 98°13′04″O  /  19.051388888889, -98.217777777778 Idioma oficial Español Entidad Localidad  • País   México  • Estado Puebla  • Municipio Puebla Presidente municipal Claudia Rivera Vivanc...
Read more

Musa

Image
Para el género de plantas, véase Musa (planta). Apolo y la Nueve Musas En la mitología griega, las musas (en griego antiguo μοῦσαι « mousai» ) son, según los escritores más antiguos, las divinidades inspiradoras de las Artes: cada una de ellas está relacionada con ramas artísticas y del conocimiento. Son hijas de Zeus y de Mnemósine, compañeras del séquito de Apolo, dios olímpico de la música y patrón de las bellas artes, quien tuvo romances con cada una de ellas, dejando descendientes. Bajaban a la tierra a susurrar ideas e inspirar a aquellos mortales que las invocaran. En la época más arcaica eran las ninfas inspiradoras de las fuentes, en las cuales eran adoradas. Finalmente, alrededor de los siglos VIII-VII a. C. [ 1 ] ​ prevaleció en todo el territorio de la Hélade la adoración de las nueve Musas, que son Calíope, Clío, Erato, Euterpe, Melpómene, Polimnia, Talía, Terpsícore y Urania. El culto a las musas era originalmente de Tracia y Beocia, y fueron de vital impo...
Read more