8
votes
5answers
522 views

Is there a built in function to obtain the back diagonal of a matrix?

Given the following matrix: m = Array[Subscript[a, #, #2] &, {4, 4}] how can I find the skew diagonal or anti-diagonal or back diagonal of the matrix ...
8
votes
2answers
753 views

OpenSCAD like functionality with Mathematica?

I keep seeing reference to use of Mathematica as a CAD tool (for instance: http://www.makerbot.com/support/guides/design/). I'd like to use it as such if feasible, but I'm having trouble locating ...
8
votes
1answer
638 views

How to map rotate, pan, zoom to manipulate controls

I am wondering if there is a way to restrict the motion of the rotate mouse cursor in when moving around a 3d plot. For example, I want the y direction of the cursor to correspond to pulling the z ...
7
votes
1answer
253 views

Import iTunes xml data and convert it into a dataset or table

I have an xml file with song data from iTunes (https://dl.dropboxusercontent.com/u/1012958/iTunes%20Library.xml) and I'd like to import it to Mathematica to do some statistics. I get an XMLObject like ...
6
votes
2answers
306 views

Exporting BarChart3D as PDF produces artefacts

So I think the following image already shows the problem, similar to Avoiding white lines inside filled area in RegionPlot exported as PDF or PS the pdf export of the chart creates thin lines in the ...
5
votes
1answer
910 views

Hodrick–Prescott filter (one-sided version)

I am interested in implementing Hodrick–Prescott filter (HP filter) on my time series data in Mathematica. I know that there is already a version of two-sided original filter for Mathematica (see ...
5
votes
2answers
966 views

Extracting polygons from 3D contour plot surface

Edit: This question turned out to be two parts so I am going to make this question about only the first part a kguler provided an excellent answer. Here is a better representation. My actual data ...
3
votes
1answer
237 views

How can I create a colour image using raw black and white data? (FITS data cube)

I have a data cube containing pictures of a galaxy across a thousand wavelengths. I want to take the data for the image slides in the red and blue parts of the spectrum, and have them represented in ...
28
votes
2answers
861 views

DeleteDuplicates not deleting duplicates

It is not surprising that DeleteDuplicates[{5,5.}] returns {5,5.} because DeleteDuplicates ...
26
votes
0answers
338 views

Are greek symbols causing different evaluation?

I've updated today to Mathematica 9.0.1.0 from version 8 and found something that absolutely confuses me. Let us define a piecewise function: ...
22
votes
3answers
372 views

Efficiently appending points to a NearestFunction

I have a program which works with a list of points (in 3D, but it could be in 1D as well, it won't make a difference). Within a loop, it keeps adding new points to the list. To calculate the ...
21
votes
2answers
704 views

Is there a Mathematica barcode reader?

Is there a Mathematica barcode image reader (much like TextRecognize) that allows the user to enter an image of a barcode and then read it to get an output string?
21
votes
10answers
2k views

How to convert a hex color string to RGBColor?

For example: "#FF8000". How could I convert it to RGBColor or Hue?
20
votes
3answers
471 views

Real Numbers in the Wolfram Language

Epilog: Much of the discussion in the answers below revolves around the distinction between Real as a data type and real numbers as a domain or class of numbers (irrespective of the form in which ...
20
votes
2answers
232 views

BitShiftRight produces incorrect results in Version 10

fixed in 10.0.2 With Mathematica 10 for Mac, BitShiftRight works properly on lists of up to 100000 numbers, but appears to give incorrect results when threaded ...
20
votes
7answers
1k views

Elegant and fast way to join all string sequences

I want to do what title says: {"a","b",1,2,3,4,"a",2,2,2,"edg","?"} => {"ab",1,2,3,4,"a",2,2,2,"edg?"} in the most elegant way. For example one replacement rule for ...
20
votes
3answers
2k views

Programming a numerical method in the functional style

I am new to Mathematica and I would like to learn a bit more about functional programming. At the moment I have assignments like programming different numerical methods (for integration: ...
20
votes
5answers
1k views

In a ListPlot of LinearModelFit, Fill to the regression line

In the help for LinearModelFit, the regression line can be added to the scatter plot like this: Show[ListPlot[data], Plot[lm[x], {x, 0, 5}]] Is it possible to ...
20
votes
1answer
1k views

Using ImageCapture to access a USB webcam in linux

Is it possible to access a USB webcam through Mathmatica on Linux? When I run ImageCapture[] I get the following output ...
18
votes
1answer
444 views

Color scheme used by Colorize?

The Colorize function is often used to display the results produced by MorphologicalComponents: ...
17
votes
1answer
301 views

Why some built-in functions are slow

I just wonder why some built-in functions are slower compared to some other ways using more than one built-in functions for doing same job. consider this example: ...
17
votes
3answers
639 views

Can CDF file embedded in a web page receive external parameters?

I know that I can embed a CDF file inside a web page by using: The embed tag. An object tag with an embed tag inside (better than 1). Using the JavaScript provided by Wolfram (better than 2). My ...
16
votes
2answers
398 views

A better “VisibleSpectrum” function?

Since ColorData["VisibleSpectrum"] is wrong I would like to have a more accurate function to use. Can this information be extracted from Mathematica itself?
16
votes
0answers
157 views

A bug in the overloading of MemberQ and FreeQ for Association?

Bug introduced in 10.0.0 and fixed in 10.1.0. While answering Pattern match for nested Association I came across behavior of MemberQ and ...
16
votes
1answer
250 views

Bug in RepeatedNull?

RepeatedNull appears to be buggy (versions 8.0, and 9.0). Define f as follows: ...
16
votes
1answer
198 views

Standard message definition construct

Why are the messages almost always defined like this (at least in packages): If[Not@ValueQ[function::usage], function::usage = "Usage message"] and not just like ...
16
votes
3answers
488 views

How to get complete Documentation Center graph of guide pages?

On the very last image below you can see a typical path of walking through Documentation Center guide pages. What is the best way to get the graph data and visualize the whole structure of these ...
15
votes
1answer
134 views

Reading from a socket stream

I noticed an undocumented socket package (SocketLink) in Mathematica (Using version 10, not sure when it was actually added) and wrote a barebones HTTP responder ...
15
votes
3answers
1k views

Drawing a square root spiral

Here is a start, i'm looking for a nice way. ...
15
votes
1answer
434 views

List of atomic expressions

I was surprised to see Graph objects are atomic. Is there a way (through documentation or programmatically) to find all atomic heads? The ones I know of are: ...
15
votes
1answer
315 views

Unpacked eigenvectors of complex matrices

Edit: This bug is fixed in Mathematica 10.0.0 I want to calculate eigenvectors of a Hermitian matrix. For example ...
15
votes
1answer
411 views

Find elements in a decay chain using IsotopeData

I am trying to write a program using the Mathematica function IsotopeData, but am finding the code troublesome. Due to my (relative) familiarity with Python, I am ...
15
votes
2answers
705 views

How to define a non-standard algebra in Mathematica?

I want to define an algebra, where there are three elements: 0, 1 and $\infty$ and two operations, addition and multiplication defined, both commutative: $$\begin{align*} 0+0&=0\\ 0+1&=1\\ ...
14
votes
12answers
610 views

Join lists with nested list

Is there a way of smarter way of joining list of the form l1 = {a,{b,c}}; l2 = {d,{e,f}}; l3 = {g,{h,i}}; To obtain ...
14
votes
0answers
1k views

Mathematica performance on Mac

I recently got a trial version of both Mathematica 9 and MATLAB 13a for Windows. I was stunned by the performance difference in the Windows and the Mac version. It was a simple test in matrix ...
14
votes
6answers
570 views

How can I suppress rotation of 3D graphics?

Given a 3D image built of a combination several Graphics3D objects, is it possible to suppress rotation of the displayed image by the mouse? To be specific, here ...
14
votes
5answers
1k views

Make legend same height as plot

One common style for density plots is to have a vertical legend that is the same height as the plot itself. Some example density plots from Google Image search: How can we make DensityPlots with ...
14
votes
1answer
583 views

Detecting and counting signals in list data: checking pulse rate

Hope this isn't too much of a basic question: I'm looking for some Mathematica functions, but I don't know which ones. Background I recently read about a simple technique for reading your body's ...
14
votes
2answers
1k views

How to deal with complicated gaussian integrals in Mathematica?

As we know, for most Gaussian integrals, we can get the analytical result. Now I have many Gaussian integrals to treat, which have the following general form, ...
14
votes
1answer
1k views

How to install and configure Intel C++ Compiler for Mathematica correctly?

I wish to try the trial version of the latest Intel C++ Compiler for Windows with Mathematica. I have downloaded the current version of Intel® C++ Composer XE 2011 for Windows and installed only the ...
14
votes
4answers
406 views

How can we implement “Sleep Sort”?

Inspired by Implement Sleep Sort: Sleep Sort is an integer sorting algorithm I found on the Internet. It opens an output stream, and for each input numbers in parallel, delay for the number ...
13
votes
1answer
406 views

Morphological Filtering in 3D to produce skeletons

Context As a follow up of this question and that answer, I would like to identify the special lines separating 3D watersheds. These are useful in the context of astronomy to identify the ...
13
votes
3answers
397 views

How to memoize a function with Options?

Consider the following modified fibonacci function: ...
13
votes
1answer
462 views

Get the current iteration count

I would like to be able to get the current iteration count, the one that if exceeds $IterationLimit makes the evaluation stop. After not finding a magical variable ...
13
votes
6answers
662 views

How can I fill-in this Pentagram?

This is my code: Graphics[{EdgeForm[Yellow], Yellow, Polygon[Table[{Cos[t], Sin[t]}, {t, 0, 4 π, (4 π)/5}]]}] which gives this: but I want to get: How?
13
votes
3answers
881 views

How to get 2D graphics into 3D without background?

Consider the following code: ...
13
votes
3answers
2k views

Manipulating the axis on a ListLinePlot

I am trying to create a plot using ListLinePlot in which the x-axis is represented in a logarithmic scale, and is reversed (so larger values are on the right side). ...
13
votes
4answers
1k views

Is there a Mathematica/Lisp link?

I'd like to start learning Lisp as it sometimes leads to interesting answers on this site with concepts borrowed from this language, so I'm curious. As I already spend most of my programming time in ...
13
votes
2answers
439 views

How to REALLY Hold arguments and capture FullForm?

I'm trying to write an expression deconstructor or FullForm-capturer; might even call it a parser, maybe, but that might be too glorious a word. I got some great ...
12
votes
3answers
362 views

Disentangling the data

An experiment yields a functional dependence on two variables $F(x,y)$, can be imagined as a 2D map. It is known that the function can be factored as follows $F(x,y)=fx(x) gy(y) +gx(x) fy(y)$. Given ...

15 30 50 per page