# All Questions

471 views

I want to do some large data analysis, and i want to be able to import files in a fast way. I tried Import, but it is quite slow; ReadList takes half the time. This is the code I was using: ...
169 views

### Performance on Multinomial Deviate is slow

Most of the time in my program is spent on this single line of code: out = RandomVariate[MultinomialDistribution[nt, tmp]]; ...
207 views

### Simplify equations with pattern assumptions

When simplifying an expression using Simplify[expr, assumptions], the assumptions has to be explicit. Is it possible to simplify an expression with pattern ...
305 views

### How to do Cases with multiple related patterns?

I would like to write a function similar to Cases, but can search for a group of related patterns together. For example, ...
187 views

### Prevent Mathematica from “romanizing” a string of letters?

When I'm authoring in text style (Alt-7), I'll often include inline math. Whenever I enter two or more consecutive letters (e.g., $ax^2$), Mathematica will automatically "romanize" (or "un-italicize") ...
405 views

### Animation is jerky, but slider is not

When I do the following simple animation (from the book Mathematica Navigator, p. 316) the slider control changes the image smoothly, but when I play the animation it is jerky. Is there anything that ...
350 views

### Assigning an analytical approximation to the error function erf(x)

Working with some iterative integral equations, I have Gaussian density functions involved therein. Integrating the Gaussian function I obtain the error function. When I take the second integration, ...
379 views

### Concise way to generate multiset lists

I wrote the following to generate a multiset with the same number of items over a fixed range: ConstantArray[#, 3]& /@ Range[9] // Flatten ...
701 views

### Recursive function for calculating the arithmetic mean of a vector

I want to write recursive function for calculating the arithmetic mean of a vector. For $X(n)=\{1,2,3,\ldots, n\}$, the formula is ${\rm Mean}(X(n))=((n-1)\, {\rm Mean}((X(n-1))+X_n)/n$. My ...
148 views

### Cannot change ImageResolution after applying ImagePad

I want to export high-resolution images of a plot I'm making. The trouble is, the plot has a lot of extra white space around it which I get rid of via ImagePad (I ...
236 views

### Exporting graphics without X server

I have a Mathematica installation on a Linux server that is intended to be used for batch processing. Some of the things that will be processed will include rendering of graphics. However, if I use ...
129 views

### Moving a locator based on the movement of another

My problem is: I want two Locators to simulate a vector in the following sense: The first Locator is the base and the second ...
402 views

### Color of a plane in Contourplot3D

I have the following code example: ...
194 views

### Interpolating a sparse list of two-dimensional coordinates

I've run into a problem where I have an ordered array of sets of coordinates, for example: ...
644 views

### A rotation-like transform on a matrix

Do not be confused with comments, those are for previous version of the question - Kuba Imagine I have a matrix of the form: ...
154 views

### Issue with scope of variables

For the definitions, t = 1; f[x_, y_] := t (x + y); v[3] := {1, 1}; g[u_] := f[v[u][[1]], v[u][[2]]]; the following two expressions yield different results, ...
479 views

### RecurrenceTable with a recurrence function of two variables

I have to calculate the cool down process of a regenerative heat exchanger. I solved the problem in Excel before, but now I want to do it with Mathematica. I want to create a table with the variables ...
255 views

### Equating two lists, element by element

Say you have two lists: listA = {a, b, c} listB = {d, e, f} How would you produce a listC that equates each of the two's ...
310 views

### How to configure two Mathematica in different places with different settings

For some reasons, I should use two language versions Mathematica. The most reason is I want to see the comparison of Help page(English version and Chinese version) to improve my English, both are ...
187 views

### Picking certain pairs according to a condition [duplicate]

I'm a Mathematica beginner and can't find out a solution to my problem. I have a list of pairs of numbers, for example something like this, but much longer: list={{2., 3.}, {3., 2.}, {5., 4.}, {4., ...
770 views

### How can I consistently get a good logistic regression fit?

I'm executing the command NonlinearModelFit[data, c/(1 + a Exp[-b x]), {a, b, c}, x] with the data being ...
332 views

### How can you combine lines in $\LaTeX$ and lines in Mathematica?

Suppose that you want to make a report about the golden section algorithm, and you want to explain the process with text in $\LaTeX$, and in every iteration you want to show in that report the values ...
1k views

### Join a piecewise plot

I wrote some code to get a piecewise plot which is displayed correctly. Now I'd like to join the various parts of the plot, using some kind of interpolation, to get a continuous chart even though it's ...
725 views

### Save variables values and definition

I used to do a lot of programming in R and recently switched to Mathematica. One thing that bothers me is that I haven't found a way to save variables, their values and definition! Let's look at an ...
806 views

### How do I read a CSV file and remove comments from it

I have very recently started using Mathematica 9.0 Home Edition and am trying to understand it as best I can so please be tolerant ;). I have a file of data (sugar.csv) which contains blood sugar ...
504 views

### Combining and separating sums

How can I combine or separate sums in Mathematica in the way that Together or Expand work for rational expressions？ For ...
774 views

### How can I control the number format of exported data?

I'm having issues while exporting a tables of numerical values to "*.dat" data files. Here's the thing, sometimes when I export a table, I get more decimals on some random values. The problem is that ...
571 views

### How to combine some elements of a list?

In order to simplify my expression, I face a list manipulation problem. For example, given the input list ...
766 views

### Trying to plot a velocity profile in x-y plane

I have a velocity profile for two liquids on top of each other in a pressure driven channel. The profile is supposed to be parabolic. I plotted them up, but I can't manage to plot them in the x-y ...
496 views

### Deleting Print results

While playing around with $Pre and$Post I created this very annoying piece of code: ...
214 views

### how to open Hyperlinked files by default software?

Non-Mathematica formats, e.g. .doc or .txt files, are directly shown in a new notebook when I click on a hyperlink pointing at these objects. But I would rather have (for example) .doc files opened ...
446 views

### Running external pdflatex command and importing the generated PDF document

There have been a couple of questions about incorporating labels and equations that were typeset in $\LaTeX$ into a Mathematica notebook. Ideally, this requires running ...
799 views

### How can I solve Tan[t] - t == F[x] for t as a function of x?

How can I solve the equation Tan[t] - t = Ax, where A is a constant for t[x]? I know that ...
278 views

### Parallel PowerMod

Is there anyway to parallelize the PowerMod function? Here is my Left-To-Right modular exponentation: ...
3k views

### Plot Even Piecewise function

Is it possible in Mathematica to plot an even piecewise function like: $f(x) = \begin{cases} 3t , 0 \le t \le \frac{\pi}{2} \\ 3t + 6 , \frac{\pi}{2} \le t \le \pi \end{cases}$ which has ...
238 views

### Customizing FrameTicks in DistributionChart

So I have been fighting with this for a while. I'm trying to get custom frame ticks on both the left and right side of a DistributionChart. It's not going very ...
2k views

### DSolve gives complex function although the solution is a real one

I have a problem with the DSolve[] command in mathematica 8. Solving the the following 4th order differential equation spits out a complex solution although it should be a real one. The equation is: ...
2k views

### How to find palindromic numbers (Project Euler #4)?

I'm trying to solve the fourth Project Euler's problem with this: ...
519 views

### How to simplify the following trigonometry expression such that the number of used characters is minimal?

How to simplify the following trigonometry expression such that the number of used characters is minimal? (13*Cos[t] - 5*Cos[2*t] - 2*Cos[3*t] - Cos[4*t])/4 The ...
165 views

### Is there a quick way to find a built-in function by name search?

Is there a quick way to search all built-in Mathematica functions by name? Say I want to find all functions whose name contains "Graph", such as GraphPlot, NeighborhoodGraph, Subgraph, and so forth. ...
620 views

### How can I assign a Fit result to a function?

I have this code ...
205 views

Code ...
577 views

### Randomly selecting elements without repetition

I assigned energy values to each element in the array as per the program of Verbeia. The program looks like this ...
375 views

### What is the command to find function invariant?

What is the command to find function invariant? http://demonstrations.wolfram.com/AFunctionInvariantUnderAGroupOfTransformations/ what is algorithm it use to calculate this? Edit there is a book ...
222 views

### Exchange axes in ListLinePlot

I'm sorry to do this right off the bat, but I have the following set of data: ...
362 views

### Pattern test for variables during function definition

I am having a problem with pattern testing on variables during function definition ...
868 views

### Use ColorFunction in ListLinePlot with If

The following code ListLinePlot[{2, 4, 6, 8, 10, 12}, ColorFunction -> Function[{x, y}, If[x <= 3, Blue, Red]]] should produce blue lines for $x\le3$ and ...
1k views

### Embed CDF into an Apple iBook?

Edit From the comments I received and verifying the information about CDF at wolfram.com, it appears that it is presently impossible to embed CDF into iBooks. WRI does not appear to be happy with this ...