12
votes
2answers
181 views

How do you determine the optimal autocompilation length on your system

When you pack lists there is an overhead therefore packing a list with, say, 2 elements is likely to cost more than you get back in efficiency. Mathematica has default list lengths for which functions ...
13
votes
2answers
365 views

SetAttributes[f,Flat]: Why the order dependence?

I'm experiencing a strange phenomenon. Here's a (quite artificial) test case: The following definition work just fine: ...
33
votes
3answers
2k views

Custom package development: Basic steps [duplicate]

Every once in a while, I write a generic function that I use quite often for months to come. However, package development in Mathematica is not very well documented from what I can tell, and I was not ...
14
votes
2answers
2k views

How to represent and manipulate abstract indexed vector (or tensor) expressions?

I have a couple abstract indexed quantities, both differential elements $dx = dx^\mu e_\mu + x^\mu de_\mu$ $du = du^\mu e_\mu + u^\mu de_\mu$ I can compute the expression $(dx + du) \cdot (dx + du) ...
17
votes
3answers
3k views

How to export large graphics?

I'm using Raster to create large graphics (1000 by 1666), which I want to Export as a JPEG or TIFF in a resolution that can be printed in a large size, 3' by 5'. ...
19
votes
2answers
721 views

What are recommended guidelines for developing packages?

This might be of general interest – I have different questions regarding naming conventions, contexts, subcontexts, shadowing, etc., but I do feel that they are closely related, thus I don't really ...
17
votes
1answer
668 views

How do you use ssh-keys instead of a password to run a remote-kernel over ssh?

On all of the servers that I regularly interact with, I have ssh-keys setup for passwordless access via ssh. Yet, every time I attempt to start a remote-kernel over ssh, I get asked for a password ...
19
votes
5answers
514 views

Reassign values to symbols

I've got a situation where I have, say 4 symbols, a, b, c and ...
16
votes
4answers
1k views

How to get actual triangles from DelaunayTriangulation[]?

The ComputationalGeometry package has a DelaunayTriangulation[] function. It returns a list of points connected to each point, ...
16
votes
3answers
724 views

Efficient way to combine SparseArray objects?

I have several SparseArray objects, say sa11, sa12, sa21, sa22, which I would like to combine into the equivalent of {{sa11, sa12}, {sa21, sa22}}. As an example, I ...
39
votes
8answers
2k views

Updating Wagon's FindAllCrossings2D[] function

Stan Wagon's Mathematica in Action (second edition; I haven't read the third edition and I'm hoping to eventually see it), demonstrates a nifty function called ...
10
votes
2answers
396 views

Move the cursor in a notebook using the keyboard

How can I move through a notebook using only the keyboard? If one tries to use the arrow keys, the cursor tends to get "trapped" in comments and error messages.
13
votes
5answers
271 views

Is it possible to cause a notebook to be hidden when pressing the close button?

Is it possible to cause a notebook to be hidden (Visible -> False) instead of closing it when pressing the close button in the title bar? The ...
5
votes
1answer
241 views

Implementing local complements of graphs

I'm trying to write a routine which generates the local complement of a graph at a vertex. For those who don't know, the local complement for a singly-connected, undirected graph is defined as the ...
4
votes
1answer
315 views

Easiest Way to Use ShowGroupOpener in Mathematica

I currently edit manually the cell contents of a notebook (Ctrl+Shift+A or Cmd+Shift+A) to "recycle" cells containing the ShowGroupOpener option. Is there an easier way to create documents hiding ...
7
votes
1answer
234 views

Setting up TextStyle with initialization cells in Mathematica 6+

It used to be quite straightforward to change the default settings of a notebook in terms of inputs, outputs, text styles and font sizes in previous versions of Mathematica using initialization cells ...
6
votes
1answer
214 views

How to simplify expression and use HoldForm at the same time?

Hopefully a simple problem for the experts here. I have a need many times to build a symbolic expression for an equation (say a PDE) to use for plot labels in a low level function inside ...
29
votes
2answers
636 views

What is the most effective way to setup a Notebook with transparent background but solid contents?

I know there is a Notebook option WindowOpacity can be used to adjust the opacity of a whole notebook. But what I want is keeping the text and graphics and so on ...
12
votes
2answers
241 views

Tuning ParallelMap when IO and computationally bound

I'm currently doing work on processing a number of images taken frame-by-frame from a video. As a result, I have a directory of around 16K PNG images that at most ~300K. That said, I have a routine, ...
14
votes
2answers
1k views

How to combine images with the same dimensions in a grid?

I have the following images, both 480 x 270 pixels: I'd like to stitch them side by side in a 960 x 270 pixel image like so (scaled down): So far, I've been using ...
17
votes
3answers
802 views

Asynchronous evaluation: Is it possible?

Currently we have a limited number of ways to perform asynchronous evaluation. The most common is through Dynamic and ...
23
votes
2answers
430 views

How can I ensure that I am constructing patterns in the most efficient way possible?

Inspired by this answer, I am interested to know if there are best practices or rules of thumb for constructing patterns, for example for use in function definitions (...
15
votes
1answer
771 views

How to export and import Graphs with additional data?

I'm trying to export and then later import graphs with additional data added such as VertexLabels and EdgeLabels. When I export ...
13
votes
4answers
1k views

How can I extract the maximum value from a Histogram?

In Mathematica 8.04 I've created a histogram of returns on a stock using: ...
36
votes
1answer
2k views

Adaptive sampling for slow to compute functions in 2D

EDIT: Although I have posted an answer based on my current progress, this in incomplete. Please see the "open issues" section in the answer. Most plotting functions in Mathematica adjust the ...
15
votes
1answer
439 views

How to work with characters from CJK Unified Ideographs Extension B correctly?

Background: Recently I'm trying to deal with some Chinese characters which belongs to the CJK Unified Ideographs Extension B block. The motive comes from some further interest following a former ...
7
votes
1answer
232 views

Why is the Locator snapping back to the original coordinates? How can I prevent this?

Take the following code: p = {3, 3}; Graphics[Circle[{5, 5}, 5], Epilog -> Dynamic@Locator[Dynamic[p]], Axes -> True, GridLines -> {{3}, {3}}] ...
11
votes
3answers
655 views

Image levels: how to alter 'exposure' of dark and light areas?

I was working with some less than ideal photographs, and wanted to adjust them before continuing. I wanted to raise the levels of the very dark areas and lower the levels of the very light areas. I ...
30
votes
3answers
2k views

Antialiasing in 3D

Is it possible? Is it platform specific? Does it rely on the graphics hardware? Why does the antialiasing slider under Preferences > Appearance > Graphics do nothing? I remember seeing some ...
14
votes
3answers
226 views

How can I test properties of a symbol from the string name without the symbol completely evaluating

Suppose I have a few symbols, one of which has a value: {abc1, abc2 = 5, abc3}; I can use Names to get the list of names, as ...
18
votes
1answer
334 views

Is there an NDSolve`ProcessEquations analog for NIntegrate?

NDSolve has an interface for repeatedly solving an equation with different initial conditions without having to analyze the equation and set up the solving algorithm each time. This can improve ...
24
votes
5answers
3k views

What is the most efficient way to add rows and columns to a matrix?

Say I have a matrix m and a vector v. ...
18
votes
1answer
716 views

Transparent textures don't show

EDIT For now, I'm going to accept Brett's answer. It's a way to get transparency back by having 3D calculations done in software instead of hardware. It addresses the symptoms but not the ...
7
votes
3answers
146 views

How to avoid spaces between numbers when displaying TagBox(es)

The instruction : DisplayForm[RowBox[List[0,1,Superscript[2,3],Superscript[1,2],a]]] displays a gap between the first two items of the list but if one is ...
19
votes
6answers
6k views

How to find the position of elements in a list satisfying criteria

Say I have a list x={2,4,6,8,10} and I want to find out the positions of the elements that are greater than 7. ...
10
votes
5answers
517 views

How do you efficiently return all of a List but one element?

I have a problem that I am working on that requires that I compare several lists of overlapping data points. As I traverse one of the lists, I'd like to only compare those data to the other lists, and ...
22
votes
2answers
722 views

What are the most common (usual) ways to make palettes with non-trivial functionality?

What are the best (most robust and most convenient) ways to create palettes that can be installed permanently (using Palettes -> Install Palette...) and are safe ...
23
votes
4answers
954 views

How to find out the (current) free memory on the system?

Is there any way in Mathematica to find out the currently free memory on the system Mathematica runs on (like the utility free shows on the command line)? I've ...
28
votes
4answers
2k views

Importing videos in Mathematica

Mathematica's Import command is purportedly able to import .AVI files. However, I find that many files that I want to import do only result in MMA showing a blank ...
20
votes
6answers
3k views

Using ListPointPlot3D to simulate 2D plots moving in time

I wrote a 1D solver for the heat equation $u_t=u_{xx}$, and I can animate the solution using normal ListPlot command, where the x-axis is the rod length, and the ...
9
votes
2answers
170 views

How to force neat linewrapping in Print?

I am regularly annoyed by the fact, that a neatly arranged Print statement gets ruined by a large piece of data, which - instead of linewrapping "in place" - is ...
8
votes
1answer
275 views

How to check for Mathematica’s definition of XY?

The question is: Can I ask the Mathematica kernel directly what it takes as the definition of the built-in symbol XY? After all this has to be in the kernel. And if the documentation is not giving any ...
54
votes
5answers
28k views

Get a “step by step” evaluation in Mathematica

Is it possible in Mathematica to get a step-by-step evaluation of some functions; that's to say, outputting not only the result but all the stages that have led to it? Example : Let's say I want to ...
36
votes
3answers
2k views

How to find out which method Mathematica selected?

There are commands like NonlinearModelFit[] or NDSolve[] that have the option Method it ...
53
votes
5answers
4k views

ListPlot: Plotting large data fast

Mathematica produces fantastic-looking graphics, but it can be slow on large data sets. Here is an example for a (random) time series: ...
21
votes
3answers
1k views

Sum over n variables

What is the most painless way to sum over n variables, for example, if the range of summation is $i_1 < i_2 < i_3 < \dots < i_n$, where $n$ is an argument of the function in question? Is ...
17
votes
5answers
464 views

Change syntax from other programs to mathematica syntax

Is there a good way to transform syntax from other computer algebra systems or from latex to mathematica syntax?
24
votes
1answer
420 views

which is better, using Assert[] or manual checks on arguments and other computations?

I never used Asserts in Mathematica, but trying to see what advantage they have over just argument check and additional definitions of the function to capture unwanted input. For example, which one ...
16
votes
2answers
697 views

Plot Option Precedence while combining Plots with `Show[]`

I like to build sophisticated plots by combining simpler ones with Show[]. Typically this involves setting non-default Plot-Options with the different ...
29
votes
3answers
2k views

Saving Mathematica kernel state?

If I save a notebook, I only save what I see. That is, if I close Mathematica and reopen the notebook later, all previous calculations are lost, except for those things I've output. Now I know that ...

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