# All Questions

356 views

### Graphics3D from Mathematica to SolidWorks (for 3D-printing)

I have an 3D Graphic generated with Mathematica's Graphics3D, and want to use it later in SolidWorks. SolidWorks files are usually *.stp, *.step, *.stl extentions. google search hasn't given me a ...
122 views

Just try this example: Export["a.txt", "这乱码问题该怎么解决呢\n***\n怎么解决嘛"] ReadList["a.txt", Record] ...
34 views

### Unexpected results from Thread [duplicate]

I've run into an issue where threading two lists with a generic function, f: Thread[f[{{1,1}, {2, 2}, {3, 3}}, {4, 5, 6}]] ...
59 views

### Visualizing vectors [closed]

How to visualize a set of vectors with 3 coordinates $(x,y,z)$, e.g.,$(1,1,1), (1,-1,-1),(-1,1,-1),(-1,-1,1)$? In fact there are many of them. I try the function "Graphic3D" with the following code ...
142 views

### Generating $n$ random samples every time

Is it possible to generate $n$ random samples, and always ensure that $n$ samples are generated? eg For $n=5$: ...
1k views

### Faster way to compute the distance from a point to a surface in 3D

I am trying to compute the shortest distance between a point and a triangle in 3D ...
120 views

### Bug in ListVectorPlot?

Trying to evaluate the following expression kills my kernel (Mathematica 8.0.0.0): ...
61 views

### Inconsistent behavior of Assuming[] in combination with Simplify[]

The following integral gives the correct result ...
137 views

### NDSolve::ndsz problem

I'm using NDSolve to solve a set of coupled differential equation which depend on a variable x. I noticed that when I set the range of x from a small value to a large value, I obtain solutions. But ...
122 views

### When exporting text, how can I set the line separator?

I want to export a string for a bash script. The terminal is naturally very picky when it comes down to the "\n\r" vs "\n", Windows vs. Linux, new line issue. How can I teach Mathematica to use "\n" ...
86 views

### Place symbols from small to big

I am wondering how to compare the different values of ω I derived in this code, and place them in order as follows. (use Print ...
243 views

### random split a dataset

I've got a very simple problem, but not so trivial. I need to split a dataset (input and output data) in three part randomly: training set 70%, validation set 20% and is test set 10%. First of all ...
88 views

### RegionPlot not working as expected

I was trying to evaluate the following expression: RegionPlot[a > 0 && 2 a + b == 0, {a, -2, 2}, {b, -1.5, 1}, PlotLegends -> "Expressions"] ...
121 views

### Computing a sum

I'm trying to make Mathematica compute this sum: Sum[(-1)^k (n - k)^2 Binomial[2 n, k], {k, 0, n}] As is, I get an awful formula: ...
419 views

### Showing the empty space in a Graphics3D plot

I would like to be able to visualize the empty space in a Graphics3D plot. For example, if I plot hexagonally close packed spheres using something like: ...
72 views

### Plotting Phase Space [duplicate]

I have these two Equ' $$x'[t]=Sin[y]$$ $$y'[t]=Cos[x]$$ and im trying to plot the phase space(plane) for this system... ive tryed Equationtrekker but cant seem to find the way to use it this way... ...
123 views

### Edit Automatic PlotRange

if I have a plot let us say Plot[x^2 - 5 x - 10, {x, 0, 8}] I want o check if there is a way to know the automatic plot range and to add or subtract from that ...
53 views

### sum polynomial H(x,y) [closed]

I want to write and evaluate an expression something like $$H_1=\sum_{i+j=0}^3 e_{ij}x^iy^j$$ or $$H=\frac{\sum_{i+j=0}^3 e_{ij}x^iy^j}{\sum_{i+j=0}^3 a_{ij}x^iy^j}$$ with correct syntax.
182 views

### Strange behavior of Reduce with a cubic equation

This equation: $(\frac{-a}{x})^2=\sqrt{\frac{1}{x}}$ at $a > 0$ and $x > 0$ has a clear solution $x=a^{4/3}$, doesn't it? However, ...
47 views

### Quoting definition explicitly

I'm trying to quote a definition using DownValues, OwnValues, etc. Everything seems to be fine, except for temporary symbols' ...
176 views

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168 views

### How to correct this, f[a_] := FindRoot[eq == 0, {x, 0.5}], where eq contains a parameter $a$, without using eq[a]?

I want to solve an equation with a parameter $a$, and define the result as a function of $a$. It is something like this: ...
276 views

### Reversing Autocorrect, aka how to find the word that was supposed to be there

When I receive messages from people using their smartphones I usually see typos and, worst, typos corrected by Autocorrect. Now, I receive messages in English, which is not my first language. I can ...
132 views

### FullSimplify inconsistent

I'm having problems using FullSimplify to simplify a differential equation. The expression is simplifying just as I would like when I express a variable ...
47 views

### how to define roots of an equation as a function? [closed]

I need to solve an equation depending on 3variables in only one variables and define the roots as a function of the remaining variables? I used some thing like that: ...
328 views

### Plotting a Spericon and Bipyramid with 100 faces

I would like to plot convex polyhedron with 100 faces, which could be used as a die. My first attempt was asking for Conway's Hecatohedron. Unfortunatly, it can not be used as a die. Now there are ...
130 views

### how can I make a control for my vector equation in my simulation?

I'm trying to build a control selector or menu for equations to put into my curvature simulations. However all the code I've tried hasn't worked.Does anyone know how I could make a control selector or ...
141 views

### Why does GraphicsGrid rescale 3d plots?

In the documentation for GraphicsGrid, it says By default, GraphicsGrid will display graphics at their specified sizes So why does it rescale the 3d plots ...
63 views

### DownValues Type Access and Timing

I definitely use so much DownValues structure for some many applications like to replace some common structures in a some way. It seems that DownValues is so fast for access, and set. My question is ...
81 views

### How do I show cross sections of a basic shape using calculus? [closed]

Assume I have an object whose radius is modeled by the function $x^2$. Using calculus and circular cross-sections, the object's volume is given by $\pi\int_a^b(x^2)^2dx$. But given an arbitrary ...
48 views

### Correctly substituting a matrix into a scalar equation [duplicate]

I am having trouble correctly substituting a matrix into an (originally) scalar equation. For example: A = {{3, 1}, {1, 2}} cp = CharacteristicPolynomial[A, x] ...
193 views

### Plotting John Conway's Hecatohedron

John Conway has given an explanation how a regular Hecatohedron (polyhedron with 100 faces) looks like: http://www.ics.uci.edu/~eppstein/junkyard/hecatohedron.html Conway explains: Here's a ...
34 views

### How to generate Koch curve in mathematica [duplicate]

How is done in Mathematica to generate the curve? Exists in the fractal geometry Koch curve, consisting of partitioning a line segment of lngitud 1 in three equal parts, by removing the central part ...
447 views

### High-quality RegionPlot3D for logical combinations of predicates

Unlike RegionPlot, RegionPlot3D copes poorly with logical combinations of predicates (...
72 views

### Viewpoint options for a 3D plot [duplicate]

Let's say I created a 3D plot in Mathematica. It's not oriented the way I want it, so I manually rotate it (in the output cell) to a desired view. (I tried playing with some view options in the code, ...
65 views

### Simplification of linear algebra [duplicate]

I have a few vectors defined as V1 = Array[v1,3] V2 = Array[v2,3] V3 = Array[v3,3] And I am trying to solve a very simple equation along the lines of ...
123 views

### Show that three given vectors lie on a line, a plane, or span 3-space

Given three vectors, {2, 0, 0}, {0, 2, 2}, {2, 2, 3}, how could I see if they are all on the ...
80 views

### N-level exponential moving average

If anyone knows how to write a mathematica code for n-level exponential moving average or someone has written already the code ?
120 views

### Calculate the algebraic multiplicity of known eigenvalues of a large, sparse matrix

I have a large (and sparse) matrix with size 1000x1000 -- 10000x10000. I believe i know all eigenvalues for the matrices. All entries are integers and so are the eigenvalues. I want to check this by ...
139 views

### Cropping a non-cubic lattice unit cell

I would like to crop the hexagonal close-packed system as a hexagon and not as a cube. I would like to use the following volumetricPlot already given on this ...
71 views

### ListPointPlot3D in a Manipulate

I have a program using Manipulate. The program given certain values will compute some values. I want these values to appear in a 3D list plot but the problem I am ...
38 views

### Evaluation of m.v is blocked by applying MatrixForm. Why? [duplicate]

I'm trying to understand what is happening in the notebook session below. I have a 2x2 matrix m = {{-1,-1}, {-1,-1}}. And a vector ...
89 views

### Export LocatorPane as image by button

How to Export LocatorPane as image by button or at least by something else? Kuba, thank you! Your method works in a simple case: ...
300 views

### Interpolating a plot with missing values

With data = {{1, 1}, {2, 2}, {3, 3}, {4, 4}, {5, 5}, {6, 6}, {7, 5}, {8, 4}, {10, 3}, {10, 2}, {11, 1}} and ...
224 views

### Can Mathematica do two evaluations at the same time?

When one evaluation is running, if I want do another evaluation, Mathematica will put the second one in the queue and run it after the first evaluation finish. However, the first evaluation may take ...
106 views

### plot totally fragmented, WorkingPrecision,matlab comparison

I am trying to plot ...
180 views

### Is there a better way to create my rotational-symmetric (180 degrees) rectangles?

I have created a simple way to create rotational-symmetric (180 degrees) rectangles, but my stuffit function bothers me. No matter what I tried, I couldn't get it ...
264 views

### Remove borders in a series of images

I have a series of mouse MRI images, here are two How can I automatically remove the metal cage around the mouse to make it look like this: The position of the cage is not always in exactly ...
200 views

### How do I built a zoomable Koch curve?

I'm new to Mathematica and my goal is to write a simple program in order to demonstrate self-similarity of the Koch curve by zooming in. Here is a good example of what I mean (it's a Java applet). I ...
75 views

### Highlight the same symbol throughout notebook

Once I saw people using Matlab use a keystroke shortcut that made all the same symbols as a selected symbol become blue. I am wondering is there is a function in Mathematica that is similar. If so, ...

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