# All Questions

2answers
409 views

### How can I build a GraphicsGrid of arbitrary size?

This is actually a very simple scenario, in order to make simpler this question Part I. Consider the following piece of Mathematica code ...
1answer
324 views

### Mesh inside Plot legend

I have a plot for which I would like to create an legend that is black and white printer friendly. I have seen Jen's legendmaker but I don't know how to adapt it. I need help in making the legend for ...
2answers
673 views

### Dynamically choosing which Manipulate controls to use

I have some stuff I would like to manipulate, using two different kinds of control, one at a time, using another variable as a switch. These controls are similar in principle to ...
2answers
887 views

### Manipulate a Differential Equation result

I want to Manipulate the result of Differential Equation like : ...
1answer
186 views

### How to set PageWidth when using PutAppend to append expressions to a file?

Do[ PutAppend[Table[i, {RandomInteger[100]}], "./file.m"], {i, 100} ] I'd like each inner list to always appear on the same line, but not automatically ...
1answer
185 views

### Locating Periodic Orbits

Here is the code for the numerical integration of an orbit. First the module for the definition of the equations of motion. ...
6answers
230 views

### How to build a game board [duplicate]

I have - rather lazily - constructed a chessboard like this: ...
2answers
332 views

### 3D Contour Plot parts of sphere with gradient less than 0, equal to 0 and more than 0

I want to plot only parts of the sphere of radius 1 where the gradient $\frac{\partial z}{\partial x}$ is < 0, = 0 and > 0. The full sphere is given by: ...
1answer
249 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: ...
2answers
70 views

### Unintentional function memoisation via Dynamic

I needed to display edge labels of a graph in a way that allows the edge labels to be moved. ...
2answers
502 views

### Research positions of lists of varying size

I'm new to the site and I am French, so I ask your indulgence for my future mistakes in English. I would like to optimise the following code : ...
2answers
208 views

### MathLink Graphical Output (Plots) to File

In a custom Mathematica frontend based on MathLink I try to make use of plots produced in Notebooks. The idea is to write them to files whenever they get produced. According to C-code snippets I ...
2answers
404 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 ...
3answers
334 views

### Fitting data without an equation

Let's say I have some data generated by anything. For practical sake, let's say I was able to generate a sequence of numbers through a recursion and I listed them out through a table of numbers. ...
2answers
1k views

### Can I improve the importing speed of Excel data?

I have data in an Excel spreadsheet that has 4 rows and 1,000 columns. I am using Import as follows: ...
1answer
171 views

### How can I create some shorthand notation for a custom control?

Per this question, I have created a custom graphical control object which evaluates to a list of values. I would like to be able to create such an object quickly, rather than typing some command, ...
4answers
2k views

### How do I plot x[t] vs. x'[t] (where x[t] and x'[t] are solutions to NDSolve)?

I have a differential equation which I solved using NDSolve. I can easily plot x[t] vs. t, x'[t] vs. t, but.... how do I plot x[t] vs. x'[t]? I tried using the Evaluate function to simplify things, ...
2answers
421 views

### Making a plotted curve interactive

Is it possible to make a plotted curve interactive in the sense that when hovering over it a line is drawn from the "hovered" point to one (or both) of the axes. I did do my homework, I just can't ...
4answers
5k views

### Creating a data1 versus data2 plot?

I have a table of data with multiple rows and columns, and I have to make a versus data table using two of these columns. Essentially, I have to set one column of data (column 3) as the y-axis and ...
1answer
59 views

### How to summarize the coefficient in Notation?

With the help from Stephen Luttrell in stackexchange, I can give an intuitive expression of quantum walk, as shown in the Mathematica codes below. ...
2answers
164 views

### Least Square Fitting

stuck on a mathematica assignment and could really use some help. A) Fit a function with the shape log(Y) = a0 + a1log(U) to the datapoints (log(Ui), log(Yi) with an least square fitting. Show this ...
1answer
264 views

### How can I build a GraphicsGrid of fixed size that rearranges the empty plots?

OK, let's make one final attempt; they say the third time is the lucky one! Following @rm-rf 's suggestions, I will try to be as clear as I can. My Mathematica code reads and plots simultaneously ...
0answers
281 views

### Is it possible to create an event handler for changes in values of variables?

I am creating a networking application in Mathematica that runs a non-stop simulation, and periodically receives new information from the remote server that affects the simulation. Whenever values ...
1answer
796 views

### Adding precision for the calculation of a function

I have some function $f(x)$ I wish to evaluate, which is yielding divide-by-zero errors for sufficiently large inputs. How do I increase the precision with which this function is evaluated in order ...
1answer
267 views

### How do I numerically solve a custom function?

Whenever I use functions like FindRoot or NDSolve, it sends x through the function and deals ...
2answers
312 views

### Bug in ArcLength?

fixed in 10.1 (windows) With Mathematica 10.0.2: ArcLength[Line[{{0, 0}, {1, 0}, {2, 0}}]] ArcLength[Line[{{0}, {1}, {2}}]] (* 2 *) (* 2 *) However, ...
9answers
1k views

### How to replace an element in a list based on the value of the next element?

I use Mathematica a little bit. I try to understand it, but it is hard I have a list of 5 numbers selected randomly from 0 and -1. I have to replace a 0 with a 1 when the 0 is followed by -1. My ...
1answer
541 views

### When exporting an (animated) GIF, is it possible to specify the size of the color palette?

I've exported an animation to animated GIF, which generated a 15mb file. I've been asked if I could regenerate the file, limiting it to only 16 colors, but I can't find any documentation on how I ...
4answers
571 views

### How do I introduce a new variable in a trigonometric equation?

I have the trigonometric equation \begin{equation*} \sin^8 x + 2\cos^8 x -\dfrac{1}{2}\cos^2 2x + 4\sin^2 x= 0. \end{equation*} By putting $t = \cos 2x$, I have \begin{equation*} \dfrac{3}{16} t^4+ ...
3answers
406 views

### Dataset seems unable to handle ListDensityPlot and ListContourPlot

If I create a Dataset: ...
3answers
399 views

### How can I set Grid alignments using numbers?

There is an example in the Alignment documentation (it also appears in the Grid documentation): ...
4answers
596 views

### HoldForm doesn't hold form

Bug introduced in 10.0.0 and fixed in 10.0.1 In Mathematica version 10, HoldForm no longer produces the same results as in version 8 (edit: I only have versions ...
0answers
161 views

### Exp is slower for some number ranges

I get a hit on performance with the Exp function depending on the range of my inputs. for example, with: ...
0answers
131 views

### How to keep the ctrl+shift+k help menu remain in display while typing?

In Mathematica 9, one can type ctrl+shift+k to display menu which has all the possible signatures/definitions for the function or command in question. One can ...
3answers
471 views

### Grabbing a number of characters around a string pattern

If I have some string data: text = StringTake[ExampleData[{"Text", "DeclarationOfIndependence"}], 400] "When in the Course of human events, it becomes ...
3answers
1k views

### Effective matrix power like algorithm

First example Suppose you want to calculate the 6th power of some matrix $A$. The brute force attempt of doing this is considering $$(((AA)A)A)A)A$$ which requires a total of 5 matrix ...
2answers
318 views

### Messages leak out from Block

fixed in 10.1 When assigning message to a symbol localized by Block, I would expect that this message is not accessible outside of ...
2answers
531 views

### PlotLegends -> “Expressions” not working when Plot given one function

I don't get a legend when I use the option PlotLegends -> "Expressions" when the first argument to Plot is a single function. It works OK when I give ...
3answers
251 views

### What's wrong with this pattern of the form Except[Repeated[…]]?

I'm trying to build a head that recognizes molecules. Here's the code ...
2answers
4k views

### Plotting vectors originating from the origin in 3D

I have an array of data with 3D elements. Ex: x = {{1,2,3}, {3,4,5}, {5,6,7}}. I want to show this data in 3 dimensions, such that each point in the space is shown ...
1answer
571 views

### Incorrect results for elementary integrals when using Integrate

There is a rather simple integral ($K_0$ is the 0-th order MacDonald function) $$\int_0^\infty e^{-x \cosh\xi}\, d\xi = K_0(x)$$ which mathematica cannot solve. This even though the documentation ...
1answer
884 views

### Why does CUDAQ (from CUDALink) download data from Wolfram servers?

I understand why functions like ElementData or CountryData need to download up-to-date data when first launched. However, when ...
1answer
326 views

### Count number of sublists with a total not greater than a given max

Suppose I have a list of positive integers: data={1, 1, 2, 3, 3, 3, 5, 5, 5, 7, 7, 8, 8, 9, 10, 10, 12, 16, 23} I want to count the number of subsets up to ...
1answer
2k views

### Parallelizing Numerical Integration in Mathematica

I have an ugly, six dimensional function that I need to integrate numerically. It works, but it currently take twelve hours to complete the calculation. Is there any good way to parallelize the ...
0answers
197 views

### What is ColorEqualSigns and how does one use it?

I'm setting up the SyntaxInformation for a package I'm writing and I'm struggling to understand what the "ColorEqualSigns" ...
2answers
362 views

### Why do NumberForm and Round apparently use different tie-breaking methods?

When rounding numbers (for example, rounding a real number to the nearest integer), the "round to nearest" rule is usually used. For example, 1.4 is rounded down to 1 and 1.6 is rounded up to 2. ...
4answers
960 views

### Evaluation of a triple sum does not finish in reasonable time

I'm trying to compute the following triple sum, but no result is produced within a reasonable amount of time. What to do? ...
1answer
411 views

### Evaluation indicator for a notebook

I have a GUI with a number of TabView and other Manipulate controls. Sometimes clicking from one tab view to the other can take ...
4answers
2k 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: ...
4answers
446 views

### Elegant high precision log1p?

Sometimes it is hard to understand how numerical expressions are evaluated. I remember reading claims by Wolfram on how smart the Kernel is to evaluate expressions trees numerically by recognizing ...

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