All Questions

6
votes
2answers
163 views

Simple question about startup options

This is probably fairly straightforward, but I wasn't able to find it right away. I'd like for Mathematica to display on startup the latest notebook I was working on, and nothing else. No additional ...
0
votes
2answers
551 views

Integral with the derivative of Dirac delta does not evaluate correctly?

Integrate[DiracDelta'[y - z] DiracDelta[x - z], {z, -Infinity, Infinity}, Assumptions -> x \[Element] Reals && x \[Element] Reals]
2
votes
1answer
680 views

NDSolve runs out of memory

I need to solve a second order ODE numerically. The ODE depends on two parameters (a,b). Things work fine when 'a' is small, but for large 'a' the solutions are oscillating rapidly and Mathematica ...
2
votes
1answer
4k views

How do I identify the source of a “Tag times protected” error?

I have some code that looks like Table[ a = 1; b = {2, 3} c = i;, {i, 2} ] which gives an error: Set::write: Tag Times in c {2,3} is ...
3
votes
1answer
248 views

Mathematica document not retaining margins from stylesheet when printing?

In the process of creating my resume in Mathematica, I needed to adjust the margins of the default stylesheet so that section headers would take up less whitespace. After modifying the stylesheet ...
14
votes
6answers
462 views

Splitting a list by specifying section headers

I have a list of strings called mylist: mylist = {"[a]", "a", "a", "[b]", "b", "b", "[ c ]", "c", "c"}; I would like to split ...
-6
votes
1answer
358 views

Custom File Palette

I find the default Mathematica IDE lacking. I am missing a simple project file tree on the left (as in eclipse, visual studio etc.) The following would be very cool: All your files (in a given ...
6
votes
1answer
2k views

Fixed color scale in multiple density plots

I think there should be a simple solution for my current problem, but neither StackOverflow (or the help of Mathematica) or Google have it. I have to plot multiple density plots with a color ...
4
votes
2answers
234 views

2D grid as a 2D polygonal or smooth domain

I have a series of points, as a list of pairs of real numbers, each multiple of a base value. So they represent a subset of a grid. Given that this list, when represented with ...
3
votes
2answers
360 views

Page breaks appearing as thick line on actual print-out

I'm using Insert->Page Break to do just that, but thick black lines are appearing on the actual printed copy wherever I indicated a break. Can this be turned off?
5
votes
1answer
499 views

(Efficiently) Generating graphs with vertex degree 3 for all vertices

I'm working on a graph theory problem, and given $n$ vertices, I would like to be able to generate all non-isomorphic connected graphs (not necessarily simple) with $n$ vertices, each having degree 3. ...
4
votes
2answers
2k views

Calculate mean and standard deviation from ImageHistogram

I am doing my PhD in Clinical Neuropsychology; I had someone helping me analyse images (.jpg pictures) in Mathematica, but it turns out this person made some really bad decisions, and well, now I have ...
6
votes
4answers
2k views

How to generate random directed connected graph?

How to generate random directed connected graph? I need to create graph which will pass: ConnectedGraphQ[^]
11
votes
2answers
392 views

Notebook formatting - easier descriptions for equations and results?

When I do computations in mathematica, I generally try to make it readable for myself-in-the-future. This can be a cumbersome task in mathematica, where it often requires me to switch betwee a text ...
7
votes
0answers
290 views

Cluster a signal into areas of equal intensity

Introduction I have a greyscale photograph that I want to partition into areas of equal intensity. This means, that the integral over each partition should be (roughly) equal. There is no unique ...
17
votes
1answer
1k views

How often does Mathematica contact its license server?

I know that Mathematica checks the validity of its license every time the program is launched. Say, however, that I have a valid license (which I do) and that I am running some code which takes a ...
0
votes
1answer
412 views

How to build a grid of integrand points and numerically integrate?

If I have some function I know numerically only, say f(x) and each point $x$ takes significant time to compute so I have them all stored in some file as f(1)=0.232423, f(1.1)=0.3243432,....Then is it ...
0
votes
1answer
2k views

Stategies to avoid NIntegrate::slwcon error

I am trying to numerically evaluate an integral whose integrand depends on two parameters, say $(a,b)$ and when $b\gg 1$ I suspect (although it's not guaranteed) that the integrand is very small. Thus ...
3
votes
1answer
380 views

Integrating over data points from an external source (wolfram|alpha and weather)

I moved to another city and the weather sucks. Sometimes I feel like getting sad and so I go to wolfram|alpha and check for example ${}$ ...
2
votes
1answer
671 views

'not a valid variable' error when trying to solve 13 equations with 13 variables

I want to solve 13 variables by 13 equations. And here is my program: ...
4
votes
1answer
2k views

How can I save and recall my own function?

In MATLAB, I can save and recall my own function using an M-File(function or script) How can I do something similar in Mathematica? I already searched and know how to define functions and modules ...
4
votes
0answers
84 views

Editing preset schemes [duplicate]

Mathematica has many preset schemes, for example "DarkRainbow" and "FadingRectangle": ...
1
vote
1answer
195 views

Adjust spacing between a section title and the first contained cell

In my day-to-day work with Mathematica I use a stylesheet I have derived from Mathematica's default stylesheet. One modification I would like to make to my stylesheet is to reduce the spacing between ...
8
votes
3answers
2k views

Randomly packing spheres of fixed radius within a cube

How can I have Mathematica randomly place spheres in a cube so they won't overlap? The cube is $20 \times 20 \times 20$, and the spheres have a radius of $0.7$.
7
votes
5answers
1k views

Vectors with a certain magnitude in Mathematica

For a user specified magnitude, is there a way to have Mathematica produce any 3D vector that fits that magnitude?
7
votes
1answer
183 views

Differentiate the product of some terms

How can I compute the following derivative, $$ \frac{\partial}{\partial \lambda_j} \prod_{i=1}^k (1+\lambda_i)e^{\lambda_i} \quad \text{for }\; 1\le j \le k $$ for some positive integer $k$ which is ...
3
votes
3answers
392 views

How to sum up large number of elements in a table quickly?

I have been using Mathematica for some time now but I have a feeling that I am not using it as efficiently as it could be. I have the following problem which I am unable to figure out and it would be ...
10
votes
3answers
3k views

NDSolve with Euler method

I want to solve this equation with NDSolve[] using the Euler method: x'[t] == 0.5*x[t]-0.04*(x[t])^2 with initial condition ...
9
votes
1answer
135 views

How to make certain mathematical characters be written as bold by default

In a notebook, when writing \[RightVector] over a variable I always end up bolding it to make it more visible. But it'd be easier if it could be set up to bold that ...
2
votes
1answer
198 views

Fighting Less::nord at the root: Any unintended consequences?

After being plagued too much by Less::nord and companions, I've decided to try to fight it at the root: The comparison operators. I noticed that typically, the bad ...
3
votes
0answers
82 views

Parsing subscripts when loading package files via the FrontEnd

I am working on some code, and have found it easier to use a Mathematica package because it is easier to run via command-line (lightweight) it allows for easier source versioning (Git), and it ...
7
votes
1answer
1k views

How to add more levels to Outline notebooks

The Outline stylesheet only seems to cover 6 levels of depth. Is there any way to increase that? Here's an example. Hitting tab on the last level just indents its content, but doesn't add another ...
3
votes
0answers
84 views

Sometimes notation gets auto-converted from traditional to raw input and won't convert back

For example, I'm typing this: When upon hitting the last character it gets converted to: And trying to Convert To TraditionalForm has no effect. This glitch has happened a few times and on ...
9
votes
2answers
266 views

Change associativity of the @ operator

The @ operator in Mathematica is right-associative by default, i.e. f@g@h evaluates as f@(g@h) Is it possible to make the ...
6
votes
1answer
418 views

Find all permutations with reversals / cyclic permutations removed

I have a list of all non-cyclic permutations of n labels. How can I get rid of all elements which are redundant in the sense that they are the inverse of another one. For instance if n=4, the ...
11
votes
2answers
3k views

How to calculate the mode of a probability distribution

I was wondering if there is any command to get the mode of the probability distributions. Calculating manually, the mode is (alpha-1)/(alpha+beta-2) While the mean, median or variance of the beta ...
8
votes
2answers
153 views

Substituting confidential tagged cells by a “content removed” cell

When producing a notebook with both code and text, I often end up with pieces of code, or even entire chapters, that I don't want to be shown on the final output. I generally hide or close them by ...
4
votes
1answer
160 views

Is the System Information that Mathematica displays not completely correct?

Or maybe I did not understand the meaning of Resolution. This is the code I used - SystemInformation["Devices", "ScreenInformation"] I get 120 as my system ...
6
votes
1answer
356 views

Colours in BarChart[]

This question is a follow up from this one. I want to be able to specify a list of colours for my bars in BarChart. In responses to the question I linked to, ...
2
votes
0answers
103 views

“automated” image embedding app

Based on the following image attach procedure, can a Dynamic app be developed that: at start, only shows a small import button once clicked, opens a choose image ...
18
votes
2answers
564 views

Attaching a file to a notebook

Is there a way to attach a file into a notebook and open it later with, for instance, a double click (or another action button)? In Mathematica windows version, the insert menu has the "object..." ...
2
votes
0answers
128 views

PowersRepresentations Algorithm

I'm trying to understand the mathematics behind counting the number of representations of a positive integer by $n$ distinct $k$th powers, i.e. I would really like to know how to do the Mathematica ...
2
votes
3answers
222 views

The same range on each plot in a grid

Suppose I have a bunch of graphics that I want to display in a grid: ...
4
votes
2answers
196 views

Function to select a row whose kth element is closest to a given number

I'm trying to write a function that picks out the row of a Matrix whose kth element is closest to some given number that will be given to me. So for example, ...
40
votes
9answers
2k views

Animating mathematica.se logo

As we all know our site's logo was completely generated by Mathematica. I suppose it is quite natural to make the next step -- to generate the animated version of this logo. There's a lot of space for ...
6
votes
1answer
348 views

Interactive Graph Editing with Animation

I want to make a simple interactive user interface like this: Such that when the user clicks on the "Add Edge" button, the edge specified by from and to fiels is added to the graph. The new graph ...
4
votes
1answer
272 views

Printing Block Matrices

I have a 2D matrix, such as: d=2; M=Array[a, {d^2,d^2}]; and I would like to print it in a way which emphasizes its dxd block matrix structure. If ...
0
votes
1answer
9k views

Why I get the “Set::write: ”Tag Times in is Protected." error?

Why I get the error below with this code: ...
7
votes
1answer
449 views

Communication between parallel kernels

Greetings. This is my first post here, also, I am not a seasoned programmer, so any advice pertaining to coding that is not directly related to the problem (stated below) is welcome. I am having ...
20
votes
3answers
1k views

How can I make a heatmap of a days in year?

I know Mathematica has a ListPlot for time series but does it have a function for visualizing a list of dates as a heat map like this: This idea is from D3, check it out here.

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