5
votes
0answers
226 views

Exhaustive examples of variable replacement due to nested scoping constructs

Consider the following examples, where I have replaced dollar signs in the output by a D. ...
5
votes
1answer
490 views

InstallR on OS X with external R installation

How do I InstallR on OS X to use my already installed and configured R? Simply using ...
5
votes
1answer
699 views

How to improve the solution of a double pendulum system

First, the code: ...
5
votes
1answer
441 views

Setting a Counter in Mathematica Notebook

I would like to write a book using Mathematica, but I will write one chapter on several files. How to tell Mathematica that the BookChapterNumber pointer has the ...
5
votes
1answer
692 views

Exporting Mathematica expression as SVG

I was thinking it would be nice if I could export Mathematica expressions as svg, but I am having some issues. At first blush everything seems to work fine. This piece of code does produce a svg file: ...
5
votes
2answers
430 views

How to save a web page in mathematica?

For a given web page http://www.nytimes.com/, is it possible to save it as : first: only HTML(within css) second: more elements(include pictures and so on) just like what a browser can do. ...
5
votes
3answers
960 views

position of sequence of elements in list [duplicate]

Possible Duplicate: Finding a subsequence in a list Question The position of {3, 5} is the list {1, 3, 4, 3, 5, 5, 1} is 3. How can such a position ...
5
votes
1answer
554 views
5
votes
2answers
546 views

Close subgroup of cells and keep them closed

Styles can be used to give your calculation a book-like structure; with chapters, sections and paragraphs. Closing those subgroups of cells you don't want to see is then very powerful to create visual ...
4
votes
1answer
135 views

Derivation of numerical scheme for linear transport equation on a variable stencil

The question is about automatica derivation of coefficients of numerical scheme on a variable stencil. So, lets consider 1d transport equation \begin{equation} (1)\qquad u_t+u_x=0. \end{equation} To ...
4
votes
2answers
227 views

Expand and collapse rows in a grid

Would someone have an idea on how to implement a table with rows that you can expand or collapse in a grid. An example could be found in a pivottable in Excel, for example here ...
4
votes
3answers
858 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
1answer
157 views
4
votes
1answer
199 views

Inheritance in Mathematica using pattern matching on UpValues

Edit: I think in my original post, I missed emphasizing the main point. This is mainly a pattern matching question. If you're interested in the 'why' of this question, please read the original post ...
4
votes
1answer
745 views

Testing for OLS Heteroscedasticity White's General Test

I've done my best to search the help and google White's test (http://en.wikipedia.org/wiki/White_test) in Mathematica. Can anyone point me to a function or Mathematica reference for this or do you ...
4
votes
2answers
487 views

Collatz Tool Box — any speed ups possible?

I have created a tool box for experimenting with the Collatz conjecture. Info here: Wolfram MathWorld and here: Wikipedia The patterns I have found allow us to make the conjecture jump through some ...
4
votes
3answers
789 views

Working with a database

I just started to work with a database through Mathematica. I have a large data set. I use an .mx file to store my data. Now I have to store the data in a database, ...
4
votes
3answers
1k views

Define a color function based on color samples obtained from ColorBrewer

I am quite new to Mathematica and I am searching for a way to create a smooth colormap based on the samples given by ColorBrewer. Is it possible to create a interpolated function from those sample ...
4
votes
2answers
384 views

Combinatorica: Girth[] and FindCycle[] disagreement

Warning: run the following code in a fresh Mma session, as some symbols could be shadowed (depending on your Mma version) While trying to answer this question, I fell into the following: ...
4
votes
1answer
2k views

Solve system of equations related to perspective projection

I'm trying to solve system of equations. I have 4 points before perspective projection and after and I whant to obtain matrix of perspective projection $m_{i,j}$ ($x,y,u,v$ are known , $m_{i,j}$ ...
4
votes
1answer
1k views

Incorrect solution of diffusion equation with Neumann boundary conditions

I want to set up a PDE model, which takes a two-dimensional diffusion equation into account. The key problem is that I have some trouble in solving the two-dimensional diffusion equation numerically. ...
4
votes
1answer
428 views

Running a package automatically when it's saved

When developing some new code (eg. a function to analyse something) I usually make a .m and .nb file. The code goes in to .m is then called from the .nb. But sometimes I forget to run the package ...
3
votes
1answer
145 views

How can I get “custom” controls to appear and behave like “default” controls in my Manipulate?

For various reasons I need to define some controls in my Manipulate with complex behaviors that are not (or at least I don't think can be) accomplished using the ...
3
votes
2answers
454 views

How do I display the plane of best fit in 3D?

I'm trying to display the plane of best fit in the same 3D-box. Currently, I have the following code which spits out a plot of the points in 3D. I want to have a plane of best fit, can Mathematica do ...
3
votes
1answer
1k views

Detection of horizontal lines in an image

Ok I'm trying to detect horizontal lines in an image. But the problem is that the line is quite obscure. So I'm not sure if it is even possible to extract that. I tried many different filters, but ...
3
votes
2answers
975 views

Eliminate doesn't work in Mathematica

Hello Mathematica users, I have problems trying to eliminate variable $Q(x,y)$ froma PDE, but Mathematica output is just True. The problem is that I already found ...
3
votes
2answers
2k views

Importing .txt or .csv financial data

I am trying to import some financial data exported from Excel. You can find the relevant file here : Text File or CSV File This is what the data looks like in Excel : Using the following code to ...
2
votes
3answers
446 views

Solving an equation involving an integral

How do I get the following into Mathematica, solving for $a$: $$ 0.7 = 1 - \frac{2}{a} \times \left[ \frac{1}{a} \int_0^a \frac{x}{\exp(x)-1}\mathrm dx + \frac{a}{6} - 1\right] $$
2
votes
1answer
9k views

Table - find index of the maximum element [duplicate]

Let's suppose that I have table t = {1.23, 3.4, 10, 34, 1.78, 0.98, 12.56}. To take the biggest element I can use Max[t] ...
2
votes
1answer
4k views

Forcing FindRoot to return only real solutions

FindRoot documentation reports that if the equation and the initial point are reals, the solutions are searched in the real domain. However, in the following case I ...
1
vote
1answer
308 views

Performance of compiled functions (Project Euler No14)

I was playing around with the project euler problem 14. The solution I came up with is listed below as cf1. The solution works fine but I get the compiler warning: ...
1
vote
0answers
981 views

triple NIntegrate fails

Here's m problem simpler in terms of codes ...
0
votes
3answers
561 views

Derive a smooth circle with cusp from an image

question 1 get the center (sample data) sample is the black circle with cusp. ...
28
votes
3answers
440 views

Assign a randomly generated list to variable

Bug introduced in 10.0.0 and fixed in 10.0.2 I don't know if this is a silly question, but it really baffles me. So please help me understand this behavior. ...
22
votes
1answer
557 views

Total much slower in version 10

Issue introduced in version 10, fixed in 10.0.2 Compilation nowadays may give very fast functions. Here is an example for finding the sum of a list of machine numbers, just as the built-in function ...
21
votes
2answers
1k views

Why does Mathematica give the wrong answer when integrating?

Bug introduced in 8.0 or earlier and fixed in 9.0.0 I integrate Integrate[Exp[I Cos[b - c]] Cos[b], {b, 0, 2 Pi}] Mathematica gives: ...
21
votes
2answers
488 views

Is Compress[] compatible between different Mathematica versions?

Compress[] was introduced in version 6 of Mathematica. It gives a compressed version of expressions represented as a string of ASCII characters. It preserves more ...
20
votes
1answer
633 views

Incorrect result from Integrate

Bug introduced in 8.0 and fixed in 10.0 I attempted to calculate the following integral: ...
19
votes
2answers
301 views

Dataset seems to break Information

Bug present in version 10.2 My little function, from pre-10.2 ,to turn a headed table into a Dataset. ...
18
votes
3answers
1k views

Highlighting individual countries on a world map

Consider the following list of countries which I would like to highlight on a world map: ...
18
votes
4answers
658 views

How can I influence the spaces between labels on a BarChart

I want to chart data using a BarChart, the labels on the x-axis are numbers. Unfortunately they are so close to each other it really looks strange and more like one ...
18
votes
3answers
308 views

Is there any way to allow a message to appear more than three times before General::stop shuts it off?

I have some Mathematica code that analyzes data in a database and uses Message to report when expected data is missing. By default, Mathematica will allow this ...
17
votes
3answers
612 views

Unicode-aware string functions?

I've recently discovered that ToUpperCase is quite unreliable on non-ASCII input: ...
16
votes
1answer
523 views

Is ColorDistance symmetric?

Is the function ColorDistance symmetric, i.e. is it always true that ColorDistance[a,b] == ColorDistance[b,a], as use of the ...
16
votes
1answer
519 views

Importing Zip files

Mathematica can import zipped files automatically, but when the content of the zip file it's another zipped file, I just get the list of files in the second zip: ...
15
votes
2answers
348 views

How to export textures?

Is there any object geometry format for which Mathematica supports the exporting of textures for external (non-Mathematica) use ? If not does anyone know of work arounds? All the texture primitives ...
15
votes
1answer
325 views

Bug in plotting function using FindMinimum?

Bug introduced in 10.0 and persisting through 10.3 or later While working on an answer to RegionPlot from NDSolve, I came across this strange behavior of ...
15
votes
4answers
2k views

How to change element color in Periodic Table?

The command ColorData["Atoms", "Panel"] generates a periodic table. As I don't want to reinvent the wheel, I asked myself how to change the color of each cell ...
15
votes
1answer
2k views

Numerical solution of coupled ODEs with boundary conditions

I have to solve the following set of ODEs and just can't get good results using Mathematica $$ r\frac{d}{dr}\left(\frac{1}{r}\frac{d}{dr}A(r)\right)-\xi^2F(r)^2\left(A(r)-1\right)=0 $$ $$ ...
15
votes
1answer
361 views

Modules that initialize themselves on first call

I use a lot of functions that extract a specific data item from a file with many data items. I want these functions to load data (slow) and return the item (fast) on first call, but just return the ...

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