# All Questions

329 views

### Why doesn't Roots work on a certain quartic polynomial equation?

In everything that follows I am using Roots to get the solutions to the equations. I start off with this equation: $$\frac{A}{3}x^4 - x^2 + 2ax - b^2 = 0$$ Now ...
118 views

### Comparison Operation for Nested Matrices

I have a nested matrix n as bellow ...
176 views

### When to use indexed variables

Still learning the fundamentals of the language I would like to ask you what advantages there might be in writing something like: a[1] = 2; a[2] = 4; a[3] = "x"; ...
561 views

### How to Make a change of variables

I have the following expresion ...
126 views

### Is there a package or canonical way for writing test harnesses in Mathematica?

I've written a complicated function foo.1 I'd now like to simplify this function's code, and later enhance it with more features. With each change, however, I'd ...
1k views

### Import Large Excel File

Currently, I am working on a large time series dataset, which contains 928,586 rows and 35 time intervals in columns, in excel format (.xlsx) and using Import to ...
175 views

### Omitting singularities from plot by specifying them in range

See the Mathematica 'basic plotting' documentation: http://reference.wolfram.com/mathematica/tutorial/BasicPlotting.html Scroll down to the third plot on that page, which says the following: "The ...
305 views

### Package relative file path specification

I have some packages inside a folder (named Packs) that is in the same file level of some executed package. ...
200 views

### Manipulate keeps updating due to a function

Edit: This is apparently only a problem on a mac running OSX. I am trying to use the 'stretchText' function by Jens. But when I use it in manipulate, the output keeps updating without changing ...
536 views

### Why is parallel slower?

I always assumed that distributing a computation is faster, but it isn't necessarily true. When I do Sum[i,{i,10^4}] I retrieve an answer much faster then if I do ...
538 views

438 views

### How to sort my list?

For example I have two lists of such structure L1 = {{"Australia",a1}, {"USA",a2}, {"Norway",a3},...} L2 = {{"Russia",b1}, {"Norway",b2}, {"Japan",b3},...} I ...
349 views

### How to solve an integral equation by iteration method? [duplicate]

How I can obtain $n^{th}$ approximation of the following equation $f(t)=t+\int_0^tds f(s)$ by iteration method?
173 views

### How to input and output partitioned matrices that show partitions and compute as normal?

I want to demonstrate multiplication of partitioned matrices as in the example here. Using the Insert Menu, you can build a matrix and draw lines between rows and columns. However, I want to be able ...
113 views

### Set number of columns in text-based interface

Is it possible to set the number of columns in Mathematica's text-based interface? Or disable word wrapping in the text-based interface ? Specifically, my concern is output from ...
297 views

### How does epilog position work in logplots?

I'm trying to use Epilog in my plots but the way that Epilog uses coordinate positions isn't making sense to me. As a minimal ...
299 views

### Butterworthfilter data filter

I am currently doing a signal analysis and filtering using Matlab. The filter I am using is Butterworthfilter model to filter scattered data (vector data). I am using Matlab as follows: ...
630 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: ...
748 views

### How to draw rectangle in mathematica with arrow

I have a basic question but i cant seem to find an answer for it. How do i draw a rectangle in mathematica with either clockwise or counterclockwise arrow heads. In this picture i know two points ...
224 views

### Replace rule with function? Derivatives don't evaluate

Say I have an expression (call it expr) involving a function, f[x]. I'd like to be able to evaluate that for a particular choice of f[x] without setting that choice for the whole session. I thought to ...