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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.

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1answer
34 views

How to speed up GeoWithinQ?

GeoWithinQ is a very useful function - is this point within this area? However, it is quite slow. It's not unheard of to have large numbers of points - for instance,...
0
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3answers
45 views

Checking whether the line is parallel to the plane

I have tried to write a code to check whether a line is parallel to the plane in Mathematica. Using that a plane has the normal vector of $\vec{n}=(a,b,c)$ and a line has a direction vector $\vec{L}=(...
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0answers
23 views

Table with two functions to output matrix with values

So I have a wing modeled as an .STL and I am analyzing its structure so I need its cross sectional area and moment of inertia at points along its span. I do this by moving an infinite plane across the ...
0
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1answer
36 views

Solve: line and rectangle intersections

I have been trying to find the intersections between a rectangle and a line, following the example given in the Solve function: ...
1
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1answer
57 views

ContourPlot3D in an explicit region

I would like to do a 3D contour plot over an implicit region, however, it seems that mma does not support the arguments within an implicit region for ContourPlot3D, is there any way to get over this? ...
1
vote
1answer
69 views

Converting .STL from Shell to Solid for stress analysis of wing

I'm new to Mathematica as this is the first class I've had to used it in my undergrad time as an aerospace engineer. Anyway, I have run into a problem that I can't figure out. I have created .STL's of ...
4
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4answers
193 views

How to find image of a complex function with given constraints?

I am very new to Mathematica. I have started learning it only last month. I would like to graph the image of some complex valued polynomials with some provided conditions. For example: $$ p(z_1,z_2,...
1
vote
1answer
61 views

RegionPlot of annulus gives a mesh

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? (...
3
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3answers
199 views

How to get regions to plot as graphics

I want to put an anulus in my graphics object. How can I format a region difference into a graphics primitive? ...
3
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1answer
72 views

Putting a 2D region plot under a 3D plot

I am trying to plot this 3D function over a hexagonal region: ...
3
votes
1answer
63 views

Finding the complement of a function's domain

I'm trying to find the list of x values not included in my domain of $0$ to $2\pi$. My current code is: ...
2
votes
1answer
31 views

Discretize Graphics3D with Scale and Rotate?

How can I discretize a Graphics3D object that makes use of Scale and Rotate? When I try <...
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4answers
95 views

How to extract the data points in tabular form from a 3D region plot

I want to solve an inequality e.g. RegionPlot3D[x^2 + y^2 + z^2 > 300, {x, 2, 9}, {y, 3, 10}, {z, 4, 12}] and store x, y, z...
1
vote
1answer
88 views

Parametric region cannnot be automatically discretized/not a valid region to plot

When I try to plot this simple parametric region: ParametricRegion[{x, Sin[z + t] + Sin[t - z]}, {{x, 0, 1}, {z, 0, 1}, {t, 0, 1}}]; RegionPlot[%] I get errors ...
5
votes
2answers
124 views

RegionDifference for Cylinder and Cuboid

I wish to use RegionDifference to take a cube shape out of a cylinder. First I make the cylinder and cube and combine them in ...
5
votes
2answers
168 views

Draw bounding region by list of points

Suppose you have a list of data points, either in 2D or 3D; is it possible to plot the minimal bounding region containing all the points? Ignoring holes etc.
0
votes
1answer
94 views

ImplicitRegion vs DiracDelta [closed]

I've been having troubles with numerical integration over implicit regions, so I checked in a simple example if the result coincides with integrating with a DiracDelta function, and found this rather ...
5
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2answers
124 views

RegionIntersection not returning what I expected

Consider the following implicit region defined on one variable reg = {x > 0 && x < 0} If I Reduce this system, ...
0
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0answers
25 views

Mathematica crashes with RegionPlot[implicitRegion]

I don't know why Mathematica crashes when plotting this ImplicitRegion (click here for the long expression). Once I define the variable ...
1
vote
2answers
71 views

Trouble with Calculating Area of Parametric Region

This question stems from an attempt to solve the following question: How to calculate specific area on surface of sphere? First, I parametrize a circular loop: ...
5
votes
4answers
269 views

Computing surface integral on the unit sphere

I have a function $f$ which takes three unit vectors of $\mathbb R^3$ and returns a number, so $f \colon \mathbb R^3 \times \mathbb R^3 \times \mathbb R^3 \to \mathbb R$ which is defined as $f(\...
5
votes
1answer
79 views

Construct a section (or slice) through 3D Regions

I would like to draw a section through some 3D regions. I start by making some simple 3D regions as a minimum working example. ...
4
votes
0answers
39 views

Wrong output of RegionPlot

I think Mathematica goes wrong if asked to plot this very simple region: Region2 = ImplicitRegion[x < -1 && y < -1/x, {{x, -3, 0}, {y, 0, 1}}] by ...
3
votes
1answer
75 views

RegionUnion for 3D Regions

I make two regions and then find I can't combine them using RegionUnion. Here are the two regions. ...
4
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1answer
111 views
0
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1answer
61 views

FunctionDomain - Meaning of “True” in output and documentation

Can someone tell me the meaning of True in output when I use FunctionDomain please? I guess that the meaning of ...
3
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2answers
77 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
732 views

Onion plot of a ball

Consider the following simple example. ...
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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
408 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
205 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 ...
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2answers
62 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
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1answer
54 views

Region Bounds not working on some Pyramid instances

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

Strange behaviour of RegionIntersection

Consider this list of inequalities ...
0
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1answer
42 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
139 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
427 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
95 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
41 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
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0answers
41 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
85 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
56 views

Mark the region defined by an inequality inside Plot3D

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

Distinguish between inner and outer boundary in MeshRegion

For example, this is a 2D MeshRegion with one (or more) holes in it: ...
4
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2answers
68 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
45 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
98 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
109 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
96 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
53 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
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0answers
32 views

Extra Ticks in Chart Boxes? [duplicate]

Is there a simple way to clean up the overextending ticks and highlight the line intersections? ...