11.12.2 Greatest hits from previous weeks

11.12.2.1 How to find the position of elements in a list satisfying criteria

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=180

Say I have a list  x={2,4,6,8,10}  and I want to find out the positions of the elements that are greater than 7. 
 
... 
[list-manipulation]
 

asked by PeterR https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=140 Score of 76

answered by J. M.'s missing motivation https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=50 Score of 81

11.12.2.2 Calculate the 2D Fourier transform of an Image

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=29203

I am new to Mathematica, and using version 8.0. 
 
I would like to calculate the 2D Fourier Transform of an  Image  with Mathematica and plot the magnitude and phase ... 
[image-processing] [image] [fourier-analysis]
 

asked by user8727 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=8727 Score of 21

answered by Nasser https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70 Score of 38

11.12.2.3 What are the most common pitfalls awaiting new users?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=18393

As you may already know, Mathematica is a wonderful piece of software. 
However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users. That can be clearly seen from ... 
[programming] [core-language] [faq] [guidelines]
 

asked by Dr. belisarius https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=193 Score of 554

answered by Michael E2 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4999 Score of 324

11.12.2.4 Conversion of Sine to Cosine

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=67521

I'm solving equations with many Cosines and Sines. 
And I want to convert all the Sines to Cosines using trigonometric formulas such as cos(x)=sin(x+pi/2). 
How can I do this? 
[trigonometry] [conversion]
 

asked by YongCheol Kwon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=23041 Score of 6

answered by Sjoerd C. de Vries https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=57 Score of 2

11.12.2.5 Solving $L=\frac 3  2  \sqrt 4 \pi ^2 A^2+W^2 -\frac \sqrt 5 W \sqrt 4 \pi ^2 A^2+W^2 +6 \pi ^2 A^2+3 W^2   \sqrt 2  +\frac 3 W  2 $ for $W$

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=57763

When I solve the aforementioned equation for $W$ or $A$ on Mathematica I get a long and ugly equation in return, namely one of the solutions for $W$ is: (attempt to read at your own health) 
 
... 
[equation-solving] [functions] [approximation]
 

asked by J.D'Almbert https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=19257 Score of 7

answered by Alexei Boulbitch https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=788 Score of 15

11.12.2.6 Parallel and perpendicular symbol from Mathematica to $\LaTeX$

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=46538

I want to get the following expression from Mathematica to $\LaTeX$: 
 
\begin{bmatrix} 
E_{\parallel} \\ E_{\perp} 
\end{bmatrix} 
 
I have tried to use inbuilt 'symbol' character from the special ... 
[latex]
 

asked by Steve Hatcher https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13314 Score of 21

answered by Sjoerd C. de Vries https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=57 Score of 29

11.12.2.7 Plot data from txt file?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=5910

I have data in file.txt which can be expressed by 20000x11 matrix. I do not want to import all of these data. How can I plot graph of the column 1 & column 4? 
[plotting] [import]
 

asked by Gokce https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1297 Score of 21

answered by user1066 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=106 Score of 25