3
votes
1answer
471 views

ReadList with header and foot lines

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: ...
3
votes
3answers
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]]; ...
3
votes
1answer
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 ...
3
votes
3answers
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, ...
3
votes
1answer
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") ...
3
votes
3answers
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 ...
3
votes
2answers
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, ...
3
votes
7answers
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 ...
3
votes
4answers
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 ...
3
votes
2answers
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 ...
3
votes
2answers
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 ...
3
votes
2answers
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 ...
3
votes
2answers
402 views

Color of a plane in Contourplot3D

I have the following code example: ...
3
votes
2answers
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: ...
3
votes
1answer
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: ...
3
votes
1answer
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, ...
3
votes
2answers
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 ...
3
votes
1answer
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 ...
3
votes
1answer
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 ...
3
votes
3answers
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., ...
3
votes
2answers
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 ...
3
votes
2answers
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 ...
3
votes
1answer
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 ...
3
votes
2answers
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 ...
3
votes
1answer
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 ...
3
votes
2answers
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 ...
3
votes
2answers
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 ...
3
votes
5answers
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 ...
3
votes
1answer
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 ...
3
votes
2answers
496 views

Deleting Print results

While playing around with $Pre and $Post I created this very annoying piece of code: ...
3
votes
2answers
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 ...
3
votes
1answer
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 ...
3
votes
3answers
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 ...
3
votes
0answers
278 views

Parallel PowerMod

Is there anyway to parallelize the PowerMod function? Here is my Left-To-Right modular exponentation: ...
3
votes
2answers
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 ...
3
votes
1answer
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 ...
3
votes
3answers
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: ...
3
votes
9answers
2k views

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

I'm trying to solve the fourth Project Euler's problem with this: ...
3
votes
3answers
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 ...
3
votes
2answers
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. ...
3
votes
2answers
620 views

How can I assign a Fit result to a function?

I have this code ...
3
votes
2answers
205 views

Why am I not getting a numeric response?

Code ...
3
votes
1answer
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 ...
3
votes
2answers
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 ...
3
votes
1answer
222 views

Exchange axes in ListLinePlot

I'm sorry to do this right off the bat, but I have the following set of data: ...
3
votes
2answers
362 views

Pattern test for variables during function definition

I am having a problem with pattern testing on variables during function definition ...
3
votes
2answers
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 ...
3
votes
1answer
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 ...
2
votes
1answer
155 views

Confusion with SplineFit (Angle calculation)

This question is continuation to this other one I am creating polymers (where each monomer is of equal length) using this method: ...
2
votes
1answer
60 views

How to NDSolve a set of equations, one of which itself contains NIntegrate of a desired function?

How to NDSolve a set of equations, one of which itself contains NIntegrate of a desired function waited to be solved by NDSolve first? For example, ...

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