7.13.2 Greatest hits from previous weeks

7.13.2.1 What do the X and Y axis stand for in the Fourier transform domain?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=85139

In Wolfram Mathematica the function  Fourier  has the following declaration 
 
 Fourier[list] 
 
 
And after a list is given to the ... 
[numerics] [fourier-analysis] [faq]
 

asked by user253956 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=29958 27 votes

answered by Hugh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12558 61 votes

7.13.2.2 Plot, extract data to a file

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=19859

I need to save data that Mathematica uses inside the  Plot  command. The format that I would like to have is: 
 
 x1 y1 
x2 y2 
..... 
 
 
... 
[plotting] [export]
 

asked by molkee https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5097 30 votes

answered by Mr.Wizard https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=121 47 votes

7.13.2.3 Get a "step-by-step" evaluation in Mathematica

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=148

Is it possible in Mathematica to get a step-by-step evaluation of some functions; that's to say, outputting not only the result but all the stages that have led to it? If so, how does one do it? 
 
... 
[evaluation] [interactive] [faq]
 

asked by Cydonia7 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=44 131 votes

answered by J. M.'s ennui https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=50 109 votes

7.13.2.4 How to add a vertical line to a plot

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=3561

In the plot below I would like to add two vertical lines at $x = \frac{\pi}{15} \pm \frac{1}{20}$. 
How can I do that? 
 
... 
[plotting]
 

asked by sjdh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=515 64 votes

answered by Ajasja https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=745 83 votes

7.13.2.5 Selecting every n-th element from a list

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=64003

I have a list: 
 
 data = {4, 5, 7, 8, 9, 5, 3, 2, 1, 2, 13, 12}; 
 
 
I want to take those elements in the list which are located at equal distances, say, every third ... 
[list-manipulation] [filtering]
 

asked by Suro https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=20003 37 votes

answered by Szabolcs https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12 34 votes

7.13.2.6 How to graph a sphere with cartesian equations?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=24169

I'm new to Mathematica and I need to ask how to graph a sphere, cylinder, etc.. using cartesian equations. 
 
For example in sphere's case $x^2+y^2+z^2=1$ 
 
I tried to use ... 
[plotting]
 

asked by German https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7145 7 votes

answered by Dr. belisarius https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=193 13 votes

7.13.2.7 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 4 votes

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