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3
votes
1answer
131 views

How to guarantee the point's position is fixed in the Graphics and Image

SeedRandom[8] plot = ParametricPlot[ Evaluate@BezierFunction[temPoint = RandomReal[{-50, 50}, {5, 2}]][ t], {t, 0, 1}, AxesOrigin -> {0, 0}] We can ...
3
votes
4answers
179 views

Why PolarPlot can have negative $r$?

Suppose a simple equation in Cartesian coordinate: $$ (x^2+ y^2)^{3/2} = x y $$ In polar coordinate the equation becomes $r = \cos(\theta) \sin(\theta)$. When I plot both, the one in polar coordinate ...
1
vote
1answer
63 views

A little confused about coordinate conversion

I'm not entirely sure how to convert from spherical coordinates to Cartesian coordinates, I believe the way to do it is by using the following code: ...
4
votes
1answer
93 views

Why is the range from $-\pi$ to $\pi$ in polar coordinates?

When I run this code FromPolarCoordinates /@ {{3/2, \[Pi]/3}, {3/2, (5 \[Pi])/3}} Then I search the documentation of ...
0
votes
0answers
27 views

How to refine a custom function that extract point from `BSplineCurve`

I have make a function that can extract the point from a BSplineCurve ...
2
votes
0answers
41 views

Changing from Cartesian to polar coordinates in partial differential equation [duplicate]

I have a partial differential equation: $$\left(x^2+y^2\right)\frac{{{\partial ^2}u(x,y)}}{{\partial {x^2}}} + x^2\frac{{{\partial ^2}u(x,y)}}{{\partial {y^2}}}=0$$ How to change from Cartesian to ...
3
votes
1answer
80 views

Angle between two vectors in spherical coordinates [closed]

I have two vectors: H = {1, 0, π/4}; EA = {1, 0, 0}; Which I want to be in {r, Phi, Theta} - which would should give an angle between the two vectors as ...
1
vote
1answer
114 views

Draw Vectors in Spherical Shell and then Animate

I want to draw three vectors inside a spherical shell. One of the vectors will be moving, the others will be stationary. However, the animation is the next step. For now, I would like to get the ...
8
votes
1answer
59 views

ImageForwardTransformation produces strange artifacts

I am trying to manipulate an image in equirectangular projection with ImageForwardTransformation. I want to change the projection's inclination to the ecliptic. For ...
2
votes
1answer
313 views

Map points on a square onto a Torus

I would like to create a 3D torus plot from a 2D graphic. This 2D original plot is a bit complex, and I haven't a clue how could transform it to a torus. The below code, from this article posted on ...
1
vote
1answer
64 views
9
votes
1answer
136 views

Non-rectilinear integration of InterpolatingFunction

Bug introduced in 7 or earlier and persisting through 10.3.1 [CASE:3487737] I have a 2-d array that I would like to resample into a different coordinate system and integrate along one of the new ...
15
votes
3answers
283 views

Coordinate system transformation problem (about Euler angle)

This question comes from the work that constructing the general cylinder by the NURBS. I have implemented the point-set $P_1,P_2,\cdots,P_n$ that in the $O-xyz$ plane, now I want to implement the ...
1
vote
0answers
69 views

Cylindrical Coordinates with NDSolveValue [closed]

Can anyone help me figure out how to set up a solution for NDSolveValue that incorporates the use of Cylindrical Coordinates. I tried using SetCoordinates[Cylindrical] but it is not working (as in it ...
6
votes
3answers
141 views

ListDensityPlot in Polar coordinates with a higher efficiency

I have data like this f[r,theta] and cells number are about 600*600 (uniform mesh) The original data has the property of uniform mesh for ...
6
votes
3answers
346 views

Using Grad, Div, etc in polar coordinates

I'm trying to use the newish functions Grad and Div to work with a PDE with circular or spherical symmetry and getting what looks to me like a wrong result. However, I'm not sure of this--perhaps I ...
3
votes
1answer
95 views

Integration of angular distribution along cartesian axis

I am plotting an anisotropy distribution function as color coding on the surface of a unit sphere with this code: ...
1
vote
1answer
173 views

PDB Graphics Options: Opacity and Scale to superimpose on 3D point plot

I am trying to superimpose a pdb file into a 3D plot of points extracted from the pdb model, while making the pdb somewhat transparent for easy viewing of plotted points. My problems are as follows. ...
0
votes
1answer
89 views

Why does a transform from polar coordinates using `TransformedField` not agree with by-hand calculation?

I have the following (simple) system of ODE's that I wish to express in Cartesian coordinates: \begin{align*} r' &= r(1-r)\\ \theta' &= 1 \end{align*} Working it out by hand, by ...
24
votes
1answer
1k views

Analogue for Maple's dchange - change of variables in differential expressions

Maple owns an interesting function called dchange which can change the variables of differential equations, but there seems to be no such function in Mathematica. ...
4
votes
3answers
221 views

Translating Histogram

SeedRandom[1]; RandomVariate[NormalDistribution[], 100]; Histogram[%, Automatic, "Probability"] The above code produces a histogram like I want to translate ...
1
vote
1answer
227 views

Plot a parametric equation in cylindrical coordinates

I'm looking for a way to plot this parametric equation on cylindrical coordinates. r = e^t theta = t+1 z = e^2t Any help would be appreciated
0
votes
1answer
94 views

Change of variables—Galilean transformation

I have a function of two variables, f[x, y], and I wish to do a Galilean transformation, i.e., y = z - v t, where ...
1
vote
1answer
252 views

Is there an easy way to transform unit vectors from spherical to Cartesian coordinates? [duplicate]

Is there a built-in function on Mathematica that will transform unit vectors from one coordinate system to another? I have a vector expressed in spherical coordinates, and I would like to find the ...
11
votes
1answer
427 views

How can I define or use a new coordinate system in Mathematica?

I want to use the dipole coordinate system as defined in this paper: http://arxiv.org/abs/physics/0606044 I see that Mathematica can do all kinds of vector analysis using different kinds of ...
2
votes
0answers
155 views

Von Neumann's method to generate points uniformly distributed on a region of a n-sphere surface

I am trying to generate points uniformly distributed on a region of a single n-sphere surface (all angles in hyperspheric coordinates are between 0 and Pi/2). I decided to use von Neumann's method ...
6
votes
2answers
259 views

How can I output the coordinates of a city in coordinates of the Mercator projection?

On Mathematica version 8, I would like to use CountryData and CityData to mark Paris on a polygon map of France in the Mercator ...
5
votes
1answer
103 views

How to apply a transformation to a grid?

I would like to apply a coordinate transformation, visualised as an action on a two-dimensional grid like The particular example above is $$x^\mu \mapsto \frac{x^\mu - b^\mu x^2}{1-b\cdot x+ b^2 ...
1
vote
1answer
276 views

Astronomy: Transform coordinates from horizon to equatorial

I'm using Mathematica 10. Giving a longitude & latitude on Earth, giving a local time, how can I transform Horizon Coordinte (az , alt) to Equatorial Coordinate (RA , DEC). Use function so I can ...
0
votes
0answers
37 views

coordinate system problem [duplicate]

I had an issue about the coordinate system of mathematica. I have a {800,600} image acquired with a camera. The projection matrix P of the camera is calculated using the calibration task. Now, when I ...
3
votes
0answers
106 views

My code does not give the same results on mathematica 9 and 10 [closed]

I have developed last year an algorithm using mathematica 9. In this algorithm, I remember that coordinate system of Image and Graphics are not the same. However, in mathematica 10 the coordinate ...
3
votes
2answers
183 views

Different between two graph in the Polar Plane

How can I plot $\theta=\cos r$ in polar plane? Of course I know that is different with $r=\cos \theta.$
1
vote
1answer
261 views

Plotting in Elliptical coordinate system

I want to plot an equation in elliptical coordinates. In the traditional elliptical system, Ellipse and hyperbola shares the same confocal point. Is there a plot function that draws a function in this ...
1
vote
1answer
185 views

CoordinateTransformData (cartesian to spherical)

I am using Mathematica v9.0.1.0 and wanted to compare Mathematica's CoordinateTransformData command to Matlab's cart2sph. (Note ...
10
votes
1answer
384 views

Compose many Geometric Transformations for 3D Graphics

I'm struggling to understand what would be a good way to compose several geometrical transformations to create a single TransformationFunction to be applied to a ...
0
votes
1answer
307 views

Order contour points in clockwise

I want to describe shape of an object using contour points descriptor. Given a silhouette (image black white of an object), I extrait the contour points using EdgeDetect[] fonction. After that, I need ...
6
votes
2answers
631 views

Find a right angled triangle

If I am given 10 points in the coordinate system in the for (x,y); where x is the x-coordinate and ...
4
votes
1answer
187 views

Convert Locator (x,y) values to Lat/Lon as per GetCoordinates on Map

I want to convert the (x,y) coordinates you get from using a locator on a map to Lat/Lon coordinates - exactly like the GetCoordinates tool does when you right click on a map. ...
3
votes
0answers
341 views

Derivatives with respect to Cartesian coordinates of functions in spherical coordinates

This seems to me to be a common task, and the more surprised I was to not have found much on this. Suppose I have an expression f in spherical coordinates ...
8
votes
1answer
764 views

ImageTransformation: polar to cartesian

I am working on something that requires the polar transformation of some images. I implemented this transformation with ImageTransformation: ...
8
votes
2answers
691 views

Mapping data on Archimedes' spiral

I would like to map my data on Archimedes' spiral and preserve the distance between points on the curve. The test data consists of 20 evenly spaced {x,y} ...
1
vote
1answer
316 views

Using spherical derivatives with NDSolve

I am trying to plot the path of an object around a centre of mass. Obviously this needs spherical coordinates. The problem I encounter is with the derivatives. The Derivatives in spherical coordinates ...
2
votes
1answer
226 views

Plotting in projective space

I am having difficulty figuring out how to plot to projective space. Suppose I have a region which I have plotted such as: ...
0
votes
0answers
106 views

Geometric Transformation not working - degenerate points?

I've successfully used FindGeometricTransformation to project the simplex triangle onto the x-y plane: ...
1
vote
2answers
120 views

What is the 'Mathematica-way' to test a variable transform?

Hello Mathematica experts. I would like to play around with a simple variable transformation, to test some claims about it. I wonder if there is a Mathematica-like way to do this. The specific case ...
2
votes
0answers
172 views

How to construct a coordinate system that owns detailed calibration in the 3D enviroment?

Recently,I write a program to demonstrate the forward kinematics of the SCARA robot.The code showed as below: Using this function to construct the BigArm and ...
1
vote
2answers
1k views

How to make Mathematica use the chain rule?

Lets say I have the following PDE: $$x^2 u_{xx} - u_{yy} + u_y = 0$$ And I have the following change of variables: $$ s(x,y) = x e^y \, \, \, , \, \, t(x,y) = x e^{-y}$$ How can I use Mathematica ...
5
votes
1answer
1k views
2
votes
1answer
944 views

Time derivative of unit vector in spherical coordinates

Is it possible to take a time derivative of a vector given in some curvelinear coordinate system (i.e. spherical)? Mathematica would need to take into account the time dependence of the basis vectors. ...
1
vote
1answer
169 views

CoordinateTransformData that works for any dimension

The function CoordinateTransformData in Mathematica only works for three dimension. For example, ...