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Questions tagged [regions]

Questions about functionality that defines or operates on regions (i.e., an open, connected set), including geometric, mesh-based, or data and formula-defined regions.

3
votes
2answers
69 views

How to plot space of bistable solutions?

I have the following ODE system dx1 = -0.7 x1 y2 dy1 = 0.7 x1 y2 + 1.7 (1-x1-y1) y2 - y1 dx2 = -0.7 x2 y1 dy2 = 0.7 x2 y1 + 1.7 (1-x2-y2) y1 - y2 I have found ...
5
votes
2answers
713 views

Onion plot of a ball

Consider the following simple example. ...
0
votes
0answers
18 views

Passing a list of conditions to AND [duplicate]

Say I have a list of some conditions, such as list = {y<x,x<0} And I'd like to plug this into RegionPlot, such as <...
4
votes
2answers
397 views

How would I define a region with multiple holes?

I would like to define a region consisting of a polygon with eight holes in it. This is essentially a stamped piece of metal with eight holes. ...
8
votes
2answers
194 views

Finding the point closest to a parameteric curve produced by a numerical method

Question How can I find the closest point to a parametric curve produced by a numerical method. General Context I have a parametric curve (which I will call $g$) produced from a averaging many ...
1
vote
2answers
57 views

Different BoundaryStyle for different sides of a RegionPlot

How can one Define a function in the RegionPlot that gives different BoundaryStyle for different sides? I mean ...
1
vote
1answer
48 views

Region Bounds not working on some Pyramid instances

When I compute the Region Bounds of a simple Pyramid, like: ...
0
votes
1answer
33 views

Strange behaviour of RegionIntersection

Consider this list of inequalities ...
0
votes
1answer
38 views

How can I check to see if two cylinders overlap?

Is there a simple way for me to determine if a cylinder a and cylinder b overlap in the 3D space? I have spent a few hours ...
3
votes
2answers
104 views

Label on boundary of region plot

Consider this plot RegionPlot[{n + k > 6}, {n, 0, 4}, {k, 0, 15}, BoundaryStyle -> None] I want to add a label on the boundary like in the picture. How can ...
9
votes
6answers
347 views

Finding the largest rectangular submatrix

I have a sparse non-symmetric binary matrix with a block structure. The dimensions of the matrix are thousands rows and less than one hundred columns. How do I identify the largest non-contiguous ...
1
vote
1answer
90 views

Supposedly same integral gives different results

I need to compute the number $ \sigma_U $ for every open bounded subset of $ n $-dimensional Euclidean space defined as $$ \sigma_U=\iint_Ud(x,y)\mathrm dx\mathrm dy $$ How can I compute this? For $...
2
votes
0answers
37 views

How to use DirichletCondition with DSolve and not just NDSolveValue?

I know one can use Region and DirichletCondition with NDSolveValue. But I do not know why it ...
0
votes
0answers
32 views

Use Manipulate, RegionPlot and Reduce in Mathematica 11

I used the following code in Mathematica 8 and it worked. Running the same code in Mathematica does not. I am very much open to suggestions to reach the same output plot in a clearer way. The code ...
3
votes
1answer
81 views

Creating a domain for NDSolveValue via ParametricRegion

A circular arc $R_2$ can be defined parametrically as $R_2 = \langle x(s),y(s) \rangle : s\in[-s_0,s_0]$ (see code below for specific $x,y$ definitions) where $s_0$ is given (I must make the arc this ...
3
votes
3answers
53 views

Mark the region defined by an inequality inside Plot3D

I have function like this ...
9
votes
2answers
113 views

Distinguish between inner and outer boundary in MeshRegion

For example, this is a 2D MeshRegion with one (or more) holes in it: ...
4
votes
2answers
63 views

Speeding up RegionPlot for iterated function system fractals

This is my first post here, I have the following basic code for drawing an iterated function system fractal. It works to the third step, but then for the fourth iteration it freezes my old MacBook. I ...
1
vote
1answer
36 views

Region plot in Log scale without affecting mesh functions

How can I do a region plot with its mesh function in Log scale? For example, ...
0
votes
1answer
92 views

map cellular automaton to planar surface

Im exploring possibility to apply a CA to a portion of a region in an image. Think that I can process an image to identify a region, as an example, a green area. I would like to confine that area, ...
3
votes
2answers
102 views

Remove legend if a plot in an array of plots is empty

In an array of plots of regions (inequalities) p[..] which are eventually combined using Show, how do I suppress the legend of ...
2
votes
1answer
77 views

Plot a two-set Venn diagram with proportional discs and intersection

Is it possible to plot a two-set/disc Venn diagram with proportional discs and intersection without having to use the below "trial-and-error" code? In the example below the left disc has 6 elements (...
1
vote
1answer
51 views

Legend display on mouse hover over region made using RegionPlot

Is there a way to label a region plotted using RegionPlot automatically, i.e. for the legend to appear inside the region without having to specify coordinates? ...
3
votes
0answers
31 views

Extra Ticks in Chart Boxes?

Is there a simple way to clean up the overextending ticks and highlight the line intersections? ...
0
votes
1answer
60 views

PlotRegion and colors

I have to plot about 24 different predicates using RegionPlot ...
12
votes
2answers
164 views

How to Interpolate a 3D MeshRegion?

If you were given some discrete MeshRegion called r (you don't know R): ...
3
votes
1answer
79 views

How to find the cells of a region that intersect a line?

I'm looking for the fastest way to access the mesh cell (i.e. polygon) in a Region that intersects a Line in 3D. For example, <...
1
vote
1answer
87 views

Computing area below 2D function

I'm trying to find an area (in η and y plane) in which the below function is >=0 ...
1
vote
0answers
25 views

Issue with RegionFunction in DensityPlot

I don't get why RegionFunction troncates even the places where x+y<1 ! ...
3
votes
2answers
84 views

Plot the region covered by a map?

Suppose we consider two dimensional cartesian coordinates x,y and pick a parametrization x = r Cos[phi]; y = r Sin[phi]; I ...
1
vote
1answer
82 views

DiscretizeRegion was unable to discretize the region ImplicitRegion

I'm trying to model a 3D die with ImplicitRegion[] in order to find out its center of mass. However, when I apply ...
2
votes
2answers
62 views

Vertices of a Rotated Polyhedron

I am attempting to geometrically transform a polyhedron (namely rotate and translate the polyhedron in global coordinates) and than find the new vertices. Here is what I have so far, but I am stuck at ...
0
votes
1answer
26 views

DelaunayMesh error : EmptyRegion

What is wrong with the following list of points? When I apply DelaunayMesh[listPoints] I get the error ...
6
votes
3answers
97 views

Sometimes Region can't build right region

During my work with NDSolveFEM I found strange behavior of function Region. ...
3
votes
1answer
62 views

Plot shown by Region does not show the full region

Why does the plot produced by the following code not contain the point {0. 0}? ...
3
votes
1answer
56 views

RegionCentroid issue

This example shows an unexpected result from RegionCentroid: ...
3
votes
1answer
54 views

RegionFunction doesn't work in ListContourPlot if also using ScalingFunctions

I am making a contour plot out of a list of values of the form {{x1,y1,f1},{x2,y2,f2},…} I want to plot this on a log log scale so I specify ...
0
votes
1answer
45 views

Plotting the intersection of a ball and a plane

I want to draw a semi-transparent ball and highlight its intersection with a plane. ...
0
votes
0answers
47 views

Animating a Sphere and Creating Static Plot Lines

I have a data set $\xi(t)$ for some numbers that I generated, and let's just say they're wholly positive numbers for now such that we can make $\xi$ like the following: ...
1
vote
1answer
100 views

Not getting the correct domain for an ODE [closed]

I want to find the domain of the the ODE $y\,= (y \operatorname{Ln} (y))/x$ and visualize it. A = FunctionDomain[(y Log[y])/x, {x, y}] ...
0
votes
2answers
34 views

Shading between two regions of two separate parametric curves/function

I have two long functions g12 and g14 in terms of g2: ...
0
votes
0answers
44 views

Understanding BoundaryMeshRegion error

I am trying to calculate the difference between two Cuboids: ...
1
vote
2answers
67 views

Plotting dynamic variable generated by checking Region intersections

I have been trying to plot a variable which is nested inside a manipulate. Here is a simplified version of the program. ...
1
vote
1answer
42 views

Plotting RegionPlot3D within a certain radius

I have a RegionPlot3D: ...
0
votes
1answer
79 views

Why is RegionIntersection failing on my custom Region?

I load a custom region, specified as BoundaryMeshRegion R = Import["C:\\data\\Profile.stl", "BoundaryMeshRegion"] and I try ...
0
votes
0answers
21 views

Using RegionPlot with NIntegrate causes symbolic evaluation when integrating

I am trying to plot the regions when a certain integral is positive. Because the function has many parameters I am passing the values through two sets of rules, one containing the pair of values I ...
6
votes
1answer
110 views

ElementMesh from ImplicitRegion cuts corners of region

I'm trying to define a region within a cell and below a level set of a function using ImplicitRegion and ToElementMesh. Here I ...
0
votes
2answers
45 views

How to compare ImplicitRegion with empty region?

I have the following function using ImplicitRegion: ...
1
vote
1answer
62 views

ImplicitRegion evaluates the region incorrectly when it must be empty

Consider the following implicit region: ...
1
vote
0answers
35 views

Different values of the numeric integral evaluated by using different methods

Consider the space of three variables $x,y,z$ defined in the ranges $$ \tag 1 x \in (0,\pi), \quad y \in (0,\pi), \quad z\in (0,2\pi), $$ and the following UnitStep ...