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

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9
votes
4answers
583 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 ...
28
votes
2answers
3k 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. ...
5
votes
1answer
409 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) = 0,\...
56
votes
1answer
2k views

DumpsterDoofus's captivating generative art

How can I render these beautiful images that DumpsterDoofus posted?
21
votes
4answers
3k views

Convert spectral distribution to RGB color

Presume that 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 ...
17
votes
2answers
828 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 ...
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
3answers
553 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 <...
3
votes
2answers
3k 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 ...
31
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: ...
10
votes
1answer
11k 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 ...
4
votes
3answers
229 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!
3
votes
3answers
827 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 $$\sum_{i_1+i_2+...+i_n=...
2
votes
1answer
665 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 ...
1
vote
1answer
238 views

Import camera parameters and data from *.sif image files? [closed]

By default, Andor's line of scientific cameras saves data in an apparently undocumented *.sif format. Are there any Mathematica packages or code that can help import these data? I've inherited an ...
27
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!
8
votes
1answer
622 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 ...
15
votes
4answers
1k views

List comprehension in Mathematica

Python supports a concept called "list comprehensions". Following is sample example ...
4
votes
3answers
897 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 ...
13
votes
1answer
240 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 ...
5
votes
1answer
834 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 ...
4
votes
0answers
142 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 ...
5
votes
1answer
508 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?
3
votes
2answers
337 views

Creating a bifurcation diagram of the logistics map [closed]

I am brand new to Mathematica so please keep that in mind. I've run into trouble trying to make a bifurcation diagram. Here is what I have done: I have a function $f(x)$ that relies on a value $r$ (...
1
vote
2answers
174 views

A cone being intercepted by a slanted plane

I have the 3d cone: Plot3D[-Sqrt[x^2 + y^2], {x, -20, 20}, {y, -20, 20}, Mesh -> None, BoxRatios -> {1, 1, 1}] I need a slanted plane intersecting it. ...
1
vote
2answers
486 views

DSolve bvlim error due to Boundary condition at infinity

I am solving an Ode using Mathematica that has boundary condition at infinity which is why Mathematica is showing error message. Please help to tackle this problem. ...
-1
votes
1answer
148 views

Trying to write my own Greedy/ Nearest Neighbor Algorithm

So I'm trying to write my own function and compare it to the results I have from using FindShortestTour. Does anyone know how to find the distance from each city to each of the others without ...