6.10.2 Greatest hits from previous weeks

6.10.2.1 Positioning axes labels

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=87388

I need to change the position of my axes labels such that the y-axis label is in the middle and parallel to the y-axis. I'd also like the x-axis label to be in the middle of the x-axis rather than  ... 
[plotting] [graphics]
 

asked by John_dydx https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7849 15 votes

answered by Virgil https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=27697 16 votes

6.10.2.2 Using Export[] sends the file where?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=8586

I am trying to use the Export command to convert a list of plots into a *.gif file, and the command runs and executes well, but I can't find the file! Where is it supposed to go? Did it even work? 
 
... 
[export]
 

asked by Patrick Da Silva https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1785 37 votes

answered by Vitaliy Kaurov https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13 51 votes

6.10.2.3 How to tell Mathematica that certain variables are real/imaginary, integer-valued, etc

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=66273

I'm trying to expedite some quantum mechanical calculations (expectation values etc.) by running them through Mathematica. When I say, for example, 
 
u[x_] := Sqrt[2/L] * Sin[Pi * n * x / L] 
 
 
and then  ... 
[functions] [complex] [variable-definitions]
 

asked by Matthew Brunetti https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=22304 36 votes

answered by SquareOne https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=19960 22 votes

6.10.2.4 Generate a Unit Circle Trigonometry

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=2456

Struggling often with Trigonometry I would like to have some code to generate this Unit Circle Trigonometry. Would be of great help when I need to transform some data : 
 
 
 
[graphics] [trigonometry]
 

asked by 500 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=172 18 votes

answered by Mark McClure https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=36 32 votes

6.10.2.5 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? 
 
f[x_] := (x^2 z)/((x^2 - y^2)^2 + 4 q^2 x^2) /. {y -> /15, z -> 1, q ->  ... 
[plotting]
 

asked by sjdh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=515 54 votes

answered by Ajasja https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=745 75 votes

6.10.2.6 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 element, getting the list {7, 5, 1,  ... 
[list-manipulation] [filtering]
 

asked by Suro https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=20003 34 votes

6.10.2.7 How to plot an ellipse?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=20100

I'm new to Mathematica, and I'm finding it difficult to plot an ellipse. 
I tried using 
 
Plot[(x/5)^2 + (y/3)^2 == 1, {x, -5, 5}, {y, -3, 3}] 
 
 
but I'm getting some errors. Is there something wrong  ... 
[plotting]
 

asked by Sriram https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=6075 17 votes

answered by Jens https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=245 29 votes