Questions on finding existing Mathematica implementations or expertise to address a clearly stated problem.

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50
votes
1answer
1k views

DumpsterDoofus's captivating generative art

How can I render these beautiful images that DumpsterDoofus posted?
39
votes
2answers
7k views

Image Shadow Removal in Mathematica

The task is: Image shadow removal is an important topic in image processing. If you feel curious about it, you may take a look here, or just google for it image shadow removal There are also a ...
29
votes
2answers
2k views

Playing with Matrix falling code in Mathematica

I was trying to create a Matrix falling code image with Mathematica. Here is my code: ...
25
votes
2answers
2k views

How to build a bvh (a motion capture file format) player in Mathematica?

How to build a bvh player that can be used to visualize human motions in Mathematica? Any idea or sample code would be appreciated. ...
25
votes
4answers
5k views

How to create effect like Van Gogh's stroke brush?

I need to apply Van Gogh's stroke brush effect to a random image Take the following image as an example: Thank you so much if you could help!
19
votes
3answers
2k views

Convert spectral distribution to RGB color

Presume I have a spectrum as a function of wavelength (an example being the blackbody spectrum): I want to convert that to a single RGB color to display on-screen, i.e. the "color" of that object ...
17
votes
2answers
769 views

How to perform fuzzy lookup between lists?

I have two big lists with 10,000 lines each, with product names from different databases. They have a lot of common products (50%), but they are not typed in the same way. For example there is one ...
16
votes
6answers
3k views

3D surface that looks like a virus

I have been recently using Mathematica for composing animations that are part of the supplementary information of my papers. I am currently trying to build an animation that involves a viral ...
15
votes
3answers
1k views

How can this type of optical illusion be created in Mathematica?

I see these around the web and would like to make them in Mathematica. Combining them in an array is actually quite mesmerizing!
15
votes
4answers
1k views

List comprehension in Mathematica

Python supports a concept called "list comprehensions". Following is sample example ...
12
votes
1answer
169 views

Nearest Kronecker Product

Some people (see The ubiquitous Kronecker product by Van Loan) have worked on finding two matrices $\mathbf A$,$\mathbf B$ of specified size whose tensor product $\mathbf A\otimes\mathbf B$ is closest ...
10
votes
3answers
1k views

Extract connected components from PNG image file and write to individual PNG files

Given the PNG image below with the three leaves in it, I'd like to extract each individual leaf and write it to its own PNG file, using Mathematica 9. Note that in the original image, the box bounding ...
9
votes
4answers
533 views

How to set Block local variables by code?

I need to create a user-defined Block function where the Block variables' values are defined by code. For example, imagine I ...
9
votes
1answer
9k views

Mathematica code for Bifurcation Diagram

At the moment I am trying to construct a bifurcation diagram of the iterative function $f(x)=$ $ax-1.1975x^3$. I've scoured the internet for pre-made bifurcation diagrams and found many (mostly of the ...
8
votes
1answer
479 views

How to generate nonperiodic tilings?

I need to generate nonperiodic tilings which are similar to the attached figure (kite-domino tiling). I was thinking the code is similar to the code for the Penrose tiling. However, that code is too ...
7
votes
5answers
296 views

Making a table with elements like {10i+j, i, j}

Table[10i+j,{i,4},{j,3}] will generate a table that looks like this: {{11,12,13},{21,22,23},{31,32,33},{41,42,43}} I would like ...
7
votes
3answers
392 views

Calculating average distance between maxima

I'm having trouble figuring out a way to analyze some simple data. When graphed, the data I have make a somewhat sinusoidal curve. What I want to do is to find the x-values of the maximum peaks of the ...
7
votes
3answers
460 views

Composition of mappings not working as expected

I have two functions $f,g:\mathbb{R}^2 \to \mathbb{R}^2$ and I define a third one $h:\mathbb{R}^2 \to \mathbb{R}^2$ as the composition $$h(x,y) = g(f(x,y))$$ I'm trying to get this function into ...
7
votes
3answers
3k views

Lyapunov Exponent

Does anyone know a (simple) Mathematica code for computing the Lyuponov Exponent for the Rossler System? Thank you Rossler System: ...
7
votes
1answer
388 views

How to create a Poincaré disk type kaleidoscope in Mathematica?

Creating a kaleidoscope in Mathematica is not a new topic at all, examples can be found from the links like Wolfram reference and Wolfram demonstrations. My question is how to create Poincaré disk ...
7
votes
0answers
337 views

Problems when solving a nonlinear PDE system with NDSolve

The nonlinear PDE system is actually extracted from a research paper published in 2000 Here is the paper link The authors solved the system by using an ordinary differential equation integrator in ...
6
votes
2answers
786 views

Distribution of 10 points within a unit square

Related to some packing problems, following problem arose: Distribute 10 points within a square of sides 1, so that minimal distance between them is maximized. With the help of random simulation, or ...
6
votes
2answers
380 views
6
votes
1answer
83 views

How to delay the definition of a function from the time of package initialization to when it is first called

I am writing a package where a couple defined functions take a very long time define at initialization time (because they are large CompiledFunctions). However ...
5
votes
4answers
197 views

Functional way to Climb an Association Decision Tree

Associations are nice tool to create decision trees. Here is a toy example of how I'm starting to use it: ...
5
votes
1answer
482 views

Tooltip for a ListPlot3D

I am getting stuck with figuring out how to use Tooltip for a ListPlot3D. Basically I have a list of values for the 3D plot (no ...
5
votes
1answer
438 views

Linearized Einstein Equations with Mathematica

I need to compute the linearised Einstein Equations around a fixed metric $g_{\mu \nu}$ which is not the flat metric. Someone knows any Mathematica package or a review that can help me?
5
votes
1answer
727 views

How to implement Kemeny-Young method? (rank aggregation problem)

Prehistory I am trying to make some statistical analysis of some experimental data, arises from measurements made ​​on an ordinal scale. I faced with the problem of rank aggregation: to get from ...
5
votes
1answer
317 views

How to program efficient undershoot/overshoot

I would like to solve the following boundary value problem for $y(x)$ for a fixed value of $k$ between $0 < k <1$: $$y'' + \frac{3}{x} y' - y + \frac{3}{2}y^2 - \frac{k}{2}y^3=0 \\ y'(0) = ...
5
votes
0answers
125 views

Finding quasi-cliques

What is the best way to identify quasi-cliques in a graph in Mathematica? I don't think it has been implemented, so are there any solutions to do this? Or do I have to export the graph data somehow ...
4
votes
3answers
736 views

Computing Gaussian curvature

Can Gaussian curvature $K$ be computed from WolframAlpha or any other available Mathematica program? Please indicate the program or its reference. If input ...
4
votes
3answers
221 views

Code for (a,b) with gcd(a,b)=1?

I am trying to make a big table that includes all ordered pairs (a,b) with a (1,2) (1,3) (2,3) (1,4) (3,4) (1,5) (2,5) (3,5) (4,5) (1,6) (5,6) ... Any ideas? Thanks!
4
votes
2answers
658 views

How to set up a simple Monte Carlo Simulation

there is a 1% chance that there will be a scattering event, if there is a scattering event the direction of scattering will be determined by a random sample of the custom[a_] function and if there is ...
4
votes
1answer
57 views

How to canonically reorganize a list using only a limited set of manipulations?

I want to canonically reorganize (like Sort) a sequence of four objects seq[a,b,c,d], but the only manipulations allowed are ...
4
votes
1answer
2k views

How do I hide some of Input

I have a project with a friend, and we make some work in Mathematica. He is not very good at Mathematica, and I have made some long necessary formulas we need. I would like to show what I've made but ...
4
votes
1answer
77 views

Draw lines between all neighbours

I have seen this question, but what I want is a bit different. I have a set of data (blue points) and I would like to end up with something like this: , i.e. joining each site with all its ...
4
votes
1answer
284 views

Lyapunov exponent plot

I am trying to create a Lyapunov exponent plot as a function of $\alpha$ for two functions: $$ f(x) = (\alpha + 1)x - \alpha x^{3} $$ and a piecewise function given by following Mathematica code: ...
4
votes
3answers
138 views

Help with coding triangular nodes/elements

I'm trying to write a program where it will shoot out the triangle node numbers. For example, in the picture, if we choose to divide this triangle by 5 points, then the program will return out the ...
4
votes
1answer
95 views

Adding extinction factor to Monte Carlo analysis

I'm looking to add an absorption component to this Monte Carlo analysis, essentially I want there to be a 1% chance that a photon gets absorbed at each event as it travels through the medium, once the ...
4
votes
0answers
122 views

Linearised Einstein equations

I need to compute the linearised Einstein Equations around a fixed metric $$g_{μν}=\text{Minkowski metric} + h_{μν}$$ which is not the flat metric. Does anyone know a Mathematica package or a ...
3
votes
3answers
648 views

Sum over multiple indices

I would like to be able to enter the following left hand side of an identity. I can write the right hand side (i think) but am not sure about the left. The Left hand side is ...
3
votes
1answer
132 views

Solving a system of generated equations?

I would like to generate a function in the following form, where the number of terms can be specified arbitrarily: ...
3
votes
0answers
99 views

Hopf Bifurcation for a non-linear dynamical system [closed]

I am very new to mathematica and also to Hopf bifurcation or any bifurcation for that matter. But I am trying to obtain a Hopf bifurcation for a dynamical system. Now, so far, I cannot find any ...
3
votes
0answers
56 views

Equilibrium solution to system of 4 ODEs with 6 parameters [closed]

I have the following system of 4 ODEs of 4 state variables $(M_{U},M_{R},F_{N},F_{M})$ and 6 parameters $(\alpha,b,\gamma,\mu_{M},\delta,\mu_{F})$ that I am trying to find the equilibrium solution ...
3
votes
0answers
85 views

Is there a way to do a symbolic PLUR decomposition of a matrix? [duplicate]

I am looking for a way to achieve the PLUR decomposition of a maitrx, as given in this paper here. The equivalent syntax in Maple is: ...
2
votes
6answers
179 views

Setting the elements of a list equal to elements of a different list

A = {a,b,c,d,e,f,g,h} B = {1,2,3,4,5} How would I go about setting some of the elements in list A equal to the elements in list B and then the left over elements ...
2
votes
2answers
2k views

Faster way to convert real strings into numbers [duplicate]

Working with big files, I have to convert some numbers that are in string format into real MMA numbers. I know that I can use ToExpression but it's slow when ...
2
votes
1answer
107 views

How do I make Mathematica show me the solutions that it has found while it is searching for them

How do I make Mathematica show me the solutions that it has found while it is searching for them, specifically in this: ...
2
votes
1answer
193 views

3D Vicsek Fractal Notebook

Can I get a link to a notebook that explores this fractal structure? I am specifically asking for a url to a Mathematica notebook that generates and / or visualizes this type of fractal. If that ...
2
votes
1answer
527 views

How to implement the directed Barabasi-Albert algorithm in Mathematica?

Does anyone know how to implement an efficient version of the [directed Barabasi-Albert algorithm][1] in Mathematica that scales until hundred of thousands nodes? The directed network mechanism is ...