# All Questions

0answers
3 views

### RegionPlot with ColorFunction gives ugly frame labels

I was working on a simple 2D region plot: ...
5answers
423 views

### Efficient Indexed Sort

Suppose I have a preference for animals given by: orderOfAnimals = {"dogs", "cats", "fish", "elephants", "giraffe", "hamsters", "poodles"}; I'm given many data ...
0answers
9 views

### Can Mathematica reconstruct an audio signal from a given spectrogram

I just realized that Mathematica can easily construct a spectrogram for a given .wav file. My question is, to what extent can this process be inverted in Mathematica? Namely, lets say I have the ...
1answer
31 views

### How Unevaluated works Through its Attributes?

Check this example: ...
2answers
168 views

### How to sort cells in a notebook based on cell tags?

Suppose I have a notebook with cells tagged with both numbers and words with numbers always list first, and some cells without cell tags e.g.: ...
2answers
60 views

### Why Plot does not obey the AspectRatio specification?

I am plotting the density function of a beta distribution and I specify that aspect ratio should be one. I expect the x and y axes should have the same scale (unit length), but it turns out not. How ...
1answer
40 views

### How to obtain the best possibe NonlinearFit

Here is some sample data ...
2answers
73 views

### NDSolve solution does not satisfy boundary conditions

I am trying to solve a 1st order non-linear ODE ...
0answers
42 views

### In Graphics, a button without action will not work?

A minimal example: Graphics@Button[Disk[]] will yield error message Button is not a Graphics primitive or directive. But if you drop ...
1answer
488 views

### Why is StringExpression faster than RegularExpression?

Edit: as noted by Albert Retey the performance difference is only seen when sub expression extraction is performed. If this test is used below the timings are similar: ...
1answer
60 views

### Combine Stereographic “Entity” Plot of Arctic Sea with Contour Plot

In the announcement of Mathematica 10 there were some very cool features for every geo-related researcher. Like this one what i'm trying to do is to overlay an ContourPlot onto this beautiful arctic ...
2answers
53 views

### Numerically Simulating a Simple Differential Equation: RC Circuit

I need to learn to simulate a differential equation in Mathematica. The differential equation that I need to simulate is complicated, without an analytical solution. However, I am brand new to ...
0answers
15 views

### Improving RationalInterpolation Result

The following code produces a {4,4} rational interpolation approximation accurate to 10^-6 or better over the range ...
1answer
70 views

### Visual representation of a Ranking over time (image provided)

[Disclaimer: I initially posted this question on stackOverflow 2 months ago and think it might be better suited for this forum (Original post: ...
1answer
52 views

### Building bounded polygon around heatmap (or points)

I have a set of data for world marine piracy. I'd like to build polygons encircling areas of active piracy. So to start with I get piracy data and make a heatmap from it. ...
1answer
43 views

### Find Vertex of Parabola [on hold]

A Frisbee is thrown straight up in the air from a position 2 m above ground level. Because of the wind pattern, the height, h, in metres, after time t, in seconds, is given by the formula H = 2 + 6t – ...
3answers
785 views

### Approximating an ornamental curve

How do I go about approximating this ornamental curve? Note variable thickness typical in calligraphy. Handbook and Atlas of Curves by E.V. Shikin (1995) contains many directions, including curve ...
1answer
41 views

### Calculate pixel intensity in two regions

I am just beginning to learn about image processing. I would like to know 1) how to show an original image with a visible mask of an arbitrary shape. And how to calculate the pixel intensities in the ...
2answers
77 views

### How to turn an expression into a number

I am working with a function that computes the covariance between two variables. After computing this, I'd like to use Plot or Plot3D to see how this covariance depends on the parameters of the mean ...
0answers
30 views

### Function to calculate finite difference

I wrote a function to calculate multivariate finite difference of different orders ...
1answer
53 views

### Is it possible to mark a Tree node and path to it?

I have the Tree : ...
3answers
92 views

### Matrices and Combination

When the positive integers 1 to 9, inclusive, are used exactly once as elements of a 3 x 3 matrix, what is the largest possible value of the determinant of the matrix?
0answers
37 views

### Any approximations in EulerEquations?

I am using the Lagrangian method so I can numerically solve for the equations of motion for the double pendulum. It's been done by hand a million times and in every derivation, small angle ...
1answer
30 views

### There is an higher probability to win with 3 dices versus 2 or with 4 dices versus 3?

In Dice wars, you gain a territory rolling the dices you have in an adiacent territory (almost like Risk game). If I have more options to choose, there are more chances to win with 3 dices versus 2 ...
3answers
304 views

### Replace all integers by 1?

Let list1 be a list of variables of the form {c1 a, c2 b, ...} where $a,b,...\in\mathbb{C}$ and $c1,c2,...\in\mathbb{Z}$. I am ...
1answer
26 views

### How can I use parts of lists with Dynamic?

I'm a newbie - what am I doing wrong? I want to use parts of lists (vectors) in calculations but Mathematica will not evaluate anything that involves parts of lists that update dynamically. Is there a ...
1answer
34 views

### Breaking out of NDSolve

I am solving a coupled set of differential equations with NDSolve for 6 unknown functions of time. At a certain point in time, the system hits a singular point where the potential governing the ...
0answers
30 views

### Why First (or Last) and Take are distinct functions? [on hold]

I think it would be better to make First take an optional second argument, so that First[list,n] is identical to ...
0answers
51 views

### CDF Player - MMA9 - MMA10 oddities

I'm (slowly) building a WordPress site with some didactic simulation made with Mathematica. Users can run the simulations (on-line or off-line) with the free Wolfram CDF Player. One of the last ...
0answers
16 views

### Again about a function defined by NIntegrate

I've looked on several similar questions but without success. Suppose I need to do the following (this is not a real problem, but only a scetch where an error appears): let (Kv)(x,s,t)=\int_s^t ...
0answers
26 views

### SubsetQ returns unevaluated

I am using Mathematica 10.0.1.0, on Ubuntu 14.04.1. Executing SubsetQ[{1, 2, 3}, {1}] returns the same expression unevaluated: ...
2answers
627 views

### Getting an InterpolatingFunction from a ContourPlot

I have a function, say minimizeme[Ω_][β_][ϵ_] = ϵ^2 Ω - Log[2 (Cosh[2 β] + Cosh[2 β ϵ])]/(2 β); I want to find its critical points in $\epsilon$ for a given ...
4answers
2k views

### How to generate a random tree?

Is it possible to generate a random tree without explicitly constructing a random adjacency matrix that satisfies tree properties? How about a random directed tree? Edit: incredible answer by ...
1answer
66 views

### Column Division

I'm new at Mathematica. I need to find all the reminders of a division between two integers - just like column division - and stop until I obtain a reminder equal to one of those already found. For ...
3answers
60 views

### List Manipulation Via Conditionals

I'm trying to convert one list to another by applying a condition on the list's elements. But I can't figure out how to do this in mathematica's language. Python example below ...
1answer
46 views

### How to export a ParametricPlot3D as .stl for 3D printing

I am a attempting to render and export a model lorenz attractor to .stl using Mathematica, so that I may 3D print it! I was able to come across a notebook (from a deeper end of Mathematica than I swim ...
1answer
109 views

### Is it possible to build/simulate/extract data from a System Modeler model completely inside a notebook using the MathModelica language syntax?

See examples in: http://www.mathematica-journal.com/issue/v10i1/contents/MathModelicaPaper/MathModelicaPaper_2.html It seems to be ruled out by the statement (Chapter 2 intro): "The subset of the ...
2answers
234 views

### What quantity is this “length” called?

tmp = {x, y, z}^{1, 2, 3} Times @@ tmp Length[%] This gives a length of 3. But I was expecting 1. What is exactly this "length" of x*y^2*z^3 called? I would ...
4answers
26k views

### How do I draw a pair of buttocks?

I'm trying to develop a function which 3D plot would have a buttocks like shape. Several days of searching the web and a dozen my of own attempts to solve the issue have brought nothing but two ...
2answers
43 views

### Custom list plot ticks

Not as exciting as the buttocks question, but ... For some list log plots, it is faster to calculate for certain log values. eg: ...
1answer
35 views

### Deferent results depending on the input form of the matrix [on hold]

Why is it so, N[Eigenvectors[{{1., 0.5, 4.}, {2., 1., 2.}, {0.25, 0.5, 1.}}]] returns: ...
0answers
50 views

### Blank sequences do not display anymore as continuous lines

BlankSequence[] and BlankNullSequence[] "suddenly" do not display anymore as "continuous lines" in my v.10.0.1 (OSX) (of course ...
1answer
25 views

### Convert Dynamic to Manipulate

The following code is a modification of Wolfram code I found under ClickPane Help. I want to convert from Dynamic to Manipulate to make it easier for me to add various controls. I do want to keep the ...
1answer
73 views

### How to share LineLegend among sub-figures in GraphicsGrid?

Using GraphicsGrid, I have put two figures that share the same x-axis in a row. However, I failed to let them share a common ...
0answers
34 views

### Using N with Eigenvalues [on hold]

I'm calculating eigenvalues of matrices. The problem is that it works for some parameters and not for others. The output in my .dat-data has #1 [other stuff] #1^2 ...
2answers
61 views

### Turn a string into a list of strings [on hold]

Is there a way to turn a series of letters, say: "kspe" Into a list composed of strings (not variables) in the form of ...
0answers
66 views

### What are the steps using boolean algebra for transforming one equation into another?

I have a special case where I have two equations, which I have solved in a better and quicker way, but I need to solve with Boolean algebra. Using the laws of Boolean algebra, I have to prove that ...
1answer
55 views

### How to prepare a Mma expression to insert it into Comsol?

Preamble Sometimes I have to solve nonlinear PDEs using Comsol. Often these equations I already have in Mma, written in a Mma notations. For this reason I would like to be able to transform them so ...
1answer
30 views

### The specified setting for the option FEFloatIterator cannot be used

I am currently trying to get a numerical simulation running where one variable is iterated over many orders of magnitude. As the calculation takes pretty long, I would like to display a ...
1answer
93 views

### Physics Lab with mathematica [on hold]

Well, I am very new at Mathematica. I have some datas from my physics Laboratory. I used to use physplot, a simple program to plot data points,but now I want to use Mathematica to plot those points, ...

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