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.

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3
votes
2answers
64 views

MeshRefinementFunction missing points

I'm doing some FEM on a rectangular region with a spherical cavity: ...
6
votes
1answer
62 views

RandomPoint fails with a large enough number of points

Bug introduced in 10.2.0 and fixed in 10.3.1. RandomPoint is new in 10.2.0. I have defined a simple ellipsoidal parametric region: ...
1
vote
0answers
61 views

Mapping a region [on hold]

Suppose I have a RegionPlot, and I want to produce a second graphic, but with a function $f$ applied to every point. For example, I could have the region in the complex plane $\{z \in \mathbb{C} \mid ...
0
votes
1answer
34 views

Exists[ ] statement inside RegionPlot[ ] too hard to resolve?

I've got a very complicated existential boolean expression, call it $\exists x: condition$, involving variables $p, q, $ and $x$. Is there a way to plot the region in which this statement holds ...
0
votes
0answers
50 views

NDSolve::bcedge error when solving PDE on a square region

I am solving a 2D PDE system: ...
3
votes
1answer
63 views
14
votes
2answers
260 views

How do I define a periodic region?

I'm trying to create a region of "thick" grid-lines, like so ...
4
votes
2answers
115 views

Confining/Periodic boundary conditions implementation for 2D Random Walker

I am new to Mathematica, and am having trouble implementing confining boundary conditions for a random walk simulation confining the walker to a pre-defined region (periodic boundary conditions would ...
6
votes
2answers
114 views

How to get the x-coordinate of a region by it's y-value

I get region like this: region = ConvexHullMesh[data = RandomReal[{0, 100}, {100, 2}]] // RegionBoundary Then I get a equally spaced y-value from minimum to ...
3
votes
1answer
61 views

How to transform a Plot or a ParametricPlot into a Region

I can get a Region from a Graphics like this: But how can I transform the graphics in a ...
2
votes
2answers
179 views

Converting a 3D Plot to a Region Plot [duplicate]

I have a 3D Plot with 3 separate functions for z in terms of x and y. I would like to ...
1
vote
1answer
55 views

Granularity of rounding affects whether coordinates make a Prism region

Given the following six 3D coordinate triples, ...
4
votes
0answers
45 views

How can I define geographic regions and new entities?

There are three functions (GeoListPlot, GeoGraphics and Entity) related to working with geographic regions but it is not clear from the documentation how to create new Entities or custom geographic ...
10
votes
3answers
419 views

How to find the outline of a country given the imperfect outlines of its administrative subdivisions?

I have a larger outline divided into several regions. While my data represents something else, let us think of this as the provinces/counties of a country, for the sake of simplicity. This is, for ...
5
votes
2answers
179 views

Separate boundaries of multiply connected region

I have a multiply connection two-dimensional region such as the following: br = BoundaryDiscretizeGraphics@Graphics[Disk[#, 8/9] & /@ CirclePoints[9]] I am ...
3
votes
1answer
112 views

Randomly generate points on a van der Waals surface

I'm looking to randomly place an atom $\mathbf{A}$ onto a van der Waals surface formed by atoms $\mathbf{B}$, such that the distance between the randomly-generated atom $\mathbf{A}$ and the nearest ...
14
votes
0answers
129 views

Bug in RegionMember?

RegionMember (new in V10) appears to have a bug. For some polygons it finds points that are clearly outside to be "members" of the region. This depends on the shape ...
6
votes
3answers
235 views

What is causing these artifacts in RegionPlot3D?

I have a simple program like this: ...
5
votes
2answers
145 views

RegionPlot of ImplicitRegion is incorrect

Why does RegionPlot of the ImplicitRegion give an incorrect plot? Also, will how does this affect calculations with ...
13
votes
2answers
215 views

Why is DiscretizeGraphics missing points on my curve?

I have a graphics expression which renders nicely as a closed curve when put in Graphics, I don't understand why I can't get the lines from DiscretizeGraphics or ...
5
votes
1answer
59 views

When is RegionMeasure[ImplicitRegion[…]] faster than (N)Integrate[Boole[…]]?

I wanted to use Mathematica to compute areas and volumes of various implicitly defined regions, so I ran a simple test case using the unit circle: ...
1
vote
0answers
70 views

Intersecting ellipsoids

First of all I know that findng whether two ellispoids intersect is complicated and there are specific algorithms created for this purpose (see, for instance, [1]. Actually, I am trying to follow this ...
4
votes
2answers
94 views

How to find alignments of interlocking shapes?

I'm searching for the ways to align interlocking shapes, that is, finding the locations and rotations that maximize the arc length at which they touch. For simplicity, I'm assuming 'shapes' are one ...
2
votes
0answers
47 views

DiscretizeRegion fails on two clearly intersecting cylinders

Intersecting cylinders has been on the top here lately, so it got me to thinking of this, ...
0
votes
0answers
37 views

non-intersecting cylinders and DiscretizeRegion, RegionIntersection [duplicate]

This is a sequel to my previous post. ...
1
vote
3answers
98 views

Why won't DiscretizeRegion work with a custom distance function?

I am trying (in 10.0) to create a region from a list of data points. I have created myDistance to use as the boolean test for whether or not a point should be included in the region ...
1
vote
0answers
78 views

Intersection of two volumes

I would like to know the volume of the intersection of a cone and a cuboid : ...
3
votes
1answer
63 views

Intersection of a MeshRegion and InfinitePlane

The documentation says that RegionIntersection is not implemented for MeshRegion objects embedded in 3D. But I have one such region and would like to slice it with ...
-1
votes
1answer
104 views

How to input functions into Mathematica [closed]

I need help with this assignment like asap. I've never been taught how to use this program and our math department expects us to learn how to use it, but it is just so complicated!!! Please help me ...
7
votes
3answers
893 views

Region bounded by x^2+y^2=1, y=z, x=0, z=0, in first octant

I need to draw (pencil and paper) the region bounded by $x^2+y^2=1$, $y=z$, $x=0$, and $z=0$ in the first octant. So the first assistance I asked of Mathematica is: ...
8
votes
1answer
156 views

How to discretize a BezierCurve?

Bug introduced in version 10.0 and persisting through 10.3 DiscretizeGraphics is new in 10.0. I need to create a discretized region from a ...
4
votes
2answers
119 views

Unexpected behavior of ImplicitRegion -> RegionPlot

I have two semicircles that are identical except that the second is shifted one unit to the right. ...
1
vote
0answers
57 views

Trying to obtain the properties of a strange region uses all memory

My version of Mathematica is: $Version 10.3.0 for Microsoft Windows (64-bit) (October 9, 2015) I produced a strange ...
25
votes
5answers
2k views

Generate two random numbers with constraints

I want to generate two random numbers, $p$ and $q$, between $0.5$ and $1$. They are connected by the constraint $1/(2q) > p$. How do I generate $p$ and $q$?
3
votes
1answer
133 views

Exclude one point from the RegionPlot

I'd like to ask you about the way of excluding just one point from this example: ...
7
votes
2answers
110 views

Behaviour of RegionDistance with Ellipse?

The data is: data = {{13, 60}, {36, 35}, {70, 29}, {106, 41}, {118, 72}, {94, 94}, {49, 99}, {24, 85}}; When I try to find a fit circle,So my method is work ...
0
votes
1answer
84 views

How to add Polygons (using existing Lines and Points) to MeshRegion?

I have a MeshRegion N with Points and Lines, but without Polygons. That means that MeshCells[N, 2] returns ...
0
votes
0answers
67 views

Region from Points

Is there a built-in way to define a 3D region from an arbitrary list of points. The points will represent vertices of the edges of the region and we can assume that 1) they are not all on the same ...
20
votes
2answers
566 views

Convert binary voxel image to geometric region

I have a binary voxel image which described a contiguous region in space. Example: ...
18
votes
3answers
433 views

Find the volume of Phobos and Deimos

How can we calculate the volume of a 3D object using the new-in-10 computational geometry functions? For simple objects this works: ...
5
votes
1answer
54 views

Efficient way to get adjacency information from MeshRegion

What is the most efficient way to get adjacency information from a MeshRegion, i.e. some efficient representation of which vertex is connected to which other one? ...
1
vote
1answer
92 views

How to Discretize Tube

Is there a way to outline text? In this topic,The BoundaryDiscretizeGraphics can Discretize a Text unexpectedly,It's amazing me,so as a same method I want to ...
9
votes
3answers
189 views

How to convert the binarize-picture to a Region

The Region of Mathematica is nice,and is the new conception of version 10.0.I can convenient get ...
3
votes
1answer
90 views

RegionPlot looks wrong

I have the following simple RegionPlot of a RegionUnion: ...
1
vote
2answers
114 views

RegionPlot with Assumptions

I am trying to evaluate the properties of a multivariate function $f(a,b,x,y)$ with respect to $x$ and $y$ given assumptions for $a$ and $b$. An example without $a$ and $b$. ...
2
votes
3answers
270 views

Plot Two Circles and color their difference

I am trying to plot two circles with radius 1 and another with radius 9. Both are centered at $(0,-1)$. I then want to color in the distance between the circle of radius 9 and the circle of radius 1. ...
0
votes
2answers
157 views

Parametric Region Plot

I tried to find solution in a few discussions but I couldn't solve my problem because my knowledge is basic. I have the following functions and parameters: ...
5
votes
1answer
134 views

How to plot multi-colored regions separated by InterpolatingFunction on sphere

I would like to plot a sphere with multi-colored regions separated by solutions of a differential equation (no explicit expression is available for the separating curves). The result I am after would ...
2
votes
1answer
64 views

RegionIntersection of a scaled cone? (elliptical cone)

I can generate the intersection of a line and a cone (from the example in the documentation). Is there a simple way to do the same for a line and an elliptical cone? i.e., this works: ...
7
votes
2answers
172 views

A method to discretize a three-dimensional solid

Consider the following region: ...