# All Questions

431 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 ...
316 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?
165 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 ...
108 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 ...
283 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: ...
709 views

### Constraining function found by NDSolve to stay positive

I am trying to constrain my variables in NDSolve so that they stay positive for the integration interval. Is is possible to do that? Using Assumptions as in ...
717 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 ...
180 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 ...
213 views

### DynamicModule, SaveDefinitions and global functions

Unfortunately, I had not checked stackoverflow, because there, the exact same behavior was already reported. Please see the Q&A "SaveDefinitions considered dangerous". Up-front, I'm on Ubuntu ...
426 views

### Edit Plot/Graphics after it's been drawn. [duplicate]

Sometimes I run into a situation when there are graphics objects (mostly plots) that take a while to draw. Good practice would suggest you do all your evaluation outside ...
133 views

### Annoying errors in sections of plot

Not a major problem, but for some reason, Mathematica outputs unevaluated diagonal sections in what should be a step plot: Plot[{PrimePi[x]}, {x, 0, 200}] ...
1k views

### ArcTan[z] and ArcTan[x,y], Restriction and Conversion

In Mathematica there are two different forms for the arctangent (inverse tangent), namely ArcTan[x,y] which gives the arc tangent of $y/x$, taking into account ...
323 views

### How do I evaluate a symbolic integral involving Hermite polynomials?

I want to test a difficult integral : Integral on all reals of some complicated function involving the Hermitian polynomials, exponentials, squares, factorials, and being general considering any ...
222 views

### Why the inequality does not take into account the domain?

I have this inequality: Reduce[(4000-1000k)/(k-4) < 0] and the answer is k ∈ Reals I would expect ...
418 views

### Improve the performance of solutions to Project Euler (#14)

Problem I have following code, when n<=10^5 it's not slow, but n>2*10^5 it's became very slow. I think maybe some temp value greater than 2^31-1, so make compile invalid. Could you give any idea ...
234 views

### Correlation with missing data

I have two lists, age and score, that I want to find correlation on for 50 people. For some people, the score is blank. Example data: ...
330 views

### How to rotate 3D graphics in ListAnimate … without making a mess?

Manipulate is, of course, wonderful … but there are LOTS of examples that are simply far too computationally intensive to use live real-time animations for. In such ...
1k views