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.

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0answers
27 views

ContourPlot3D with variables within a ball

My attempt is (Mathematica 12.0) ...
2
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1answer
80 views

RegionPlot3D with additional variables

Why doesn't this RegionPlot3D not plot anything? ...
3
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3answers
170 views

Strange RegionDifference output on simple example

Why is the output so irregular in the following simple example? ...
4
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2answers
80 views

How to control the spatial discretization of a 3D Region object

I am using constructive geometry to build up a complex 3D shape. I do so by combining Region objects of Graphics3D[] primitives using RegionUnion[] and RegionDifference[]. Here is the code that I use: ...
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1answer
56 views

plot and volume of y^2+z^2=1 cut by the plane y=x and x=1 in the first quadrant

I need to plot and find the volume of y^2+z^2=1 cut by the plane y=x and x=1 in the first quadrant So far, ...
1
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1answer
50 views

RegionDifference of a sphere and pyramid - Not correctly specified

I would like to cut out a pyramid from the sphere with the following but somehow I am missing something due to an error "RegionDifference object is not a correctly specified region" ...
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2answers
51 views

complex region plot - tweaking

ComplexRegionPlot[Abs[z + 1 - I] <= 1, {z, -2, 1 + 2 I}, AxesOrigin -> {0, 0}, AspectRatio -> 2/3] ComplexRegionPlot[Arg[z - 1] <= 3 Pi/4, {z, -2, 1 + 2 I}, AxesOrigin -> {0, 0}, ...
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3answers
223 views

Finding Ellipse Axes

Consider the following ellipse, generated by the bounding region of the following points ...
3
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2answers
101 views

Use a table of data to plot a region instead of RegionPlot

I have an equation that I want to plot as a region plot but it takes a long time to plot and in the future, I will need to replot it multiple times so is it possible to replot a region plot from a ...
2
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1answer
125 views

How to find the image of a region under a matrix?

I want to write code that, given a matrix, finds the image of a unit disk under that matrix. I googled this and I could not find much but this seems like such a simple task. I found the command ...
1
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0answers
44 views

Why RegionPlot plots only the first equation? [closed]

I want to RegionPlot three regions, each of them are $$t_1<t<t_2<0, \quad t<t_1<t_2<0, \quad t_2<t<t_1<0,$$ but it seems that the ...
6
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4answers
415 views

Problem with exporting RegionPlot as PDF

I have the following RegionPlot (which code I don't present since it comes from a long expression): When I right click on it (within the notebook) and try to save ...
4
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2answers
460 views

3d printing flat pattern

Four copies of a flat region defined below ( length AH = 10 mm and prism Thickness= 2 mm typically) is to be 3d printed so that edges LM,KI coincide. Writing ...
1
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2answers
87 views

NSolve unable to solve system of equations with domain specification

I have a system of two equations in two unknowns that I would like to solve with NSolve within a specified region. However, while Mathematica solves the system if I omit the domain specification, it ...
2
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3answers
135 views

Obtain Data Points (x,y) from a 2D region plot generated from an inequality

I have a code that generates a region plot modeling an aperture. I would like to generate a table of ordered pairs (x,y) for a given u that manipulates my inequality. When I attempt to great a table ...
10
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8answers
1k views

Checking if two line segments intersect

What is the fastest way of checking whether two line segments of the form Line[{p1,p2}] intersect at a point? I don't need to know what the point of intersection is,...
1
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0answers
92 views

How can I solve the 2D diffusion equation over a region that contains mobile sinks?

I am looking for guidance on how to simulate the following system in 2D. I have a region, assumed to be rectangular for simplicity. A substance is diffusing into this region from its boundary. Again ...
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2answers
107 views

How plot the domain of multivariable function? [closed]

I want to get and plot the domain of the following function with mathematica : $$Arccos(xy)$$ Any idea ?
2
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1answer
93 views

Define Implicit Region using Interpolating Function

Suppose I have a set of points $\{(x_1,x_2) : g(x_1,x_2) > f(x_1,x_2)\}$, how would I turn this into a mesh that acts as a region for PDE solvers, or even to use as a plotting region? I have tried ...
0
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1answer
76 views

RegionPlot for " < " and " <= " is the same on the boundary? [duplicate]

RegionPlot[{1 <= x < 5 && 2 < y < 5}, {x, 0.8, 5.2}, {y, 1.8, 5.2}, BoundaryStyle -> Dashed] Is there a way to use SOLID line for "less ...
1
vote
1answer
70 views

What causes RegionResize errors for maps of specific countries?

I want to resize the map of the country as below. ...
0
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1answer
60 views

Mysterious RegionDistanceFunction::regp message

Bug introduced in 12.3.1 or earlier [CASE:4853257] I encountered a strange problem with RegionDistanceFunction. Consider this list of points (I'm forced to use <...
0
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1answer
134 views

RandomPoint does not return with many region intersections

I am trying to generate random points on an n-dimensional unit sphere that satisfy a number of linear inequalities (a point $v \in \mathbb{S}^N$ has to satisfy $v \cdot x \geq v \cdot x_k$ for all $...
0
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0answers
117 views

Bug computing a Polygon area?

Why the following code works: ...
3
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2answers
112 views

Create region bounded by parametric curves

How can I define a region that is bounded by a set of parametric curves? E.g. three parametric curves - which are cubic Bezier curves - define the boundary of a shape: ...
0
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1answer
127 views

Mathematica crashes when plotting over region

Mathematica (12.0.0 or 12.3.0) crashes and kernel quits on my computer (Win 10) when I try the simple exercise of plotting over a region (taken from this Wolfram page): ...
1
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1answer
90 views

Defining a region in Mathematica

I have two functions which are eigenvalues: $$ E_+= a*x-\sqrt{(b-x^2-y^2)^2+d*(x^2+y^2)}$$ ...and... $$ E_-= a*x+\sqrt{(b-x^2-y^2)^2+d*(x^2+y^2)}. $$ How do I define a region $\left|E_{\pm}\right|<...
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1answer
100 views

NIntegrate over 2D region failed. Simple integrand. Complicated region

The integrand is simply a Gaussian curve over one of the variables PDFTheta[the_] := PDF[ NormalDistribution [0, DeltaTheta/2], the] The region of integration is ...
0
votes
1answer
84 views

How to make these lines smooth when using ContourPlot inside of a region?

Consider a region in the $(R,T)$ plane defined by the conditions $$0 < R\leq \pi,\quad |T|+R<\pi\tag{1}$$ Define $t(R,T)$ to be $$t(R,T)=\dfrac{1}{2}\left(\tan\left(\dfrac{T-R}{2}\right)+\tan\...
1
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0answers
39 views

Finding the shared edged between two polygons

Imagine I have two convex polygons pol1 and pol2 with a shared edge. Take, as an example, ...
0
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1answer
79 views

When should one use RegionFunction with ParametricPlot3D?

According to the documentation, "RegionFunction is an option for plotting functions that specifies the region to include in the plot drawn", and it can be ...
3
votes
2answers
160 views

Find intersection points between ParametricRegion and other curves

How do you instruct Mathematica to return intersection points between curves as numerical values, when using ParametricRegion to represent at least one of the ...
1
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2answers
100 views

How can I change the default color of the basic geometric regions in 2D?

I like to use the basic geometric regions in Mathematica, like Parallelogram[...], Rectangle[...], ...
4
votes
3answers
146 views

Select list points at region [closed]

If I have a list Table[{dj, di}, {dj, 0, 1, 0.2}, {di, 0, 1, 0.2}], how can I select only the points that satisfies $\left(2-\delta_{j}\right)-\sqrt{2\left(2-\...
0
votes
1answer
77 views

ParametricPlot3D with variable plot limits

I would like to use ParametricPlot3D in the following general way: ParametricPlot3D[\[Sigma][u,v],{u,0,2Pi},{v,-f[u],f[u]}]. ...
9
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1answer
211 views

DirichletCondition doesn't always work with RegionBoundary

I am trying to solve the heat equation on a circle with a square shaped hole in it. It works: ...
2
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2answers
180 views

Plot the intersection of random half-spaces

The code ...
1
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0answers
86 views

Creating a map of earth from an unknown region of the sphere

Lately I've been trying to use Mathematica to plot a map of earth. I have an analytic function from a known triangle to some part of a unit sphere, described by unknown parametrization. This function $...
2
votes
1answer
80 views

Problems plotting ImplicitRegion

I have run into some rather strange behavior regarding plotting over regions defined by ImplicitRegion. I have a condition given by ...
1
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0answers
63 views

List of conditions Plot [closed]

I made a table of conditions, namely conditions that define spheres. But I can't plot those in "RegionPlot3D", I would really like to know what I can do to surpass this problem. When I get ...
6
votes
2answers
339 views

Maximal circle packing inside a given square

How to pack n equal disks(radius a/2) with maximal area inside a given rectangle ? I'm trying to solve this problem using Mathematicas Region functions. Here my approach: Maximize the area of the ...
0
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0answers
52 views

Checking Membership of Conic Hull for Multiple Inputs

Suppose I have a given $10 \times 12$ matrix T, a $12 \times 1$ vector Subscript[\[Xi], 0], a $4 \times 12$ matrix ...
1
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0answers
21 views

How can I ask mathematica to fill in small marginal area in regionplot3d? [duplicate]

I am stuck at how to fill in some marginal area in my regionplot3d. Here is my code. ...
0
votes
2answers
123 views

Drawing the filled Julia set of a polynomial

Suppose I use JuliaSetPlot to draw the Julia set of a polynomial. Is there a way, assuming the set is connected, to fill in the region? My idea was to use ...
4
votes
1answer
94 views

Imaginary variables in ImplicitRegion

I am using the function ImplicitRegion[]. RegionPlot[ImplicitRegion[x^2 + y^2 == -1, {x, y}]] which gives me a circle, though in the documentation variables are ...
1
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0answers
32 views
1
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0answers
40 views

How to speedup RegionIntersection?

Consider a circle circle located at the origin of a coordinate frame and with a radius ROffAxisArb (it is parametrized by two ...
0
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1answer
54 views

Wrong boundary in RegionPlot after RegionUnion

I have defined three regions, Slice1, Slice2 and Slice3. ...
1
vote
1answer
62 views

How to define a polygonal region in 2D to subsequently integrate over it?

I want to integrate a function f[x,y] over a region like this. Is there any way to define the region using the vertices of the purple polygon? Then I can ...
2
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1answer
67 views

RegionPlot3D over non-rectangular range

I want to make a RegionPlot3D only in the range x + y + z < 1. The following works, but is slow and poor quality. ...

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