8.9.2 Greatest hits from previous weeks

8.9.2.1 How to make a Spherical Cow?
8.9.2.2 Is there something like DensityPlot3D to visualize atomic orbitals?
8.9.2.3 How can I transpose x and y axis on a Plot?
8.9.2.4 How do I clear all user defined symbols?
8.9.2.5 How to tell Mathematica that certain variables are real/imaginary, integer-valued, etc
8.9.2.6 How can I plot the direction field for a differential equation?
8.9.2.7 Creating a table/Matrix during a For loop
8.9.2.1 How to make a Spherical Cow?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=125043

Being a theoretical physicist, I always have a great respect for Spherical Cow. So I thought about making one myself. I am not sure how can I create (something considered to be the simplest!) this ... 
[geometry] [image3d]
 
asked by Sumit https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=8070 Score of 71
answered by andre314 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5467 Score of 78
8.9.2.2 Is there something like DensityPlot3D to visualize atomic orbitals?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=32378

I'm visualizing some hydrogen like atomic orbitals.  For looking at plane slices of the probability density, the  DensityPlot  function works well, and with something ... 
[plotting] [physics] [chemistry]
 
asked by Peeter Joot https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=10 Score of 45
answered by xslittlegrass https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1364 Score of 25
8.9.2.3 How can I transpose x and y axis on a Plot?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=18655

This question has appeared in various forms online, but I have not yet seen a complete answer, so I am posting it here. 
 
More specifically, suppose I have a function 
 
... 
[plotting] [graphics]
 
asked by merlin2011 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5619 Score of 16
8.9.2.4 How do I clear all user defined symbols?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=850

Is there some way to do this other than going to  Evaluation -> Quit kernel  and firing a new one up? 
[variable-definitions] [symbols] [faq] [clear] [persistence]
 
asked by niklasfi https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=82 Score of 101
answered by Artes https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=184 Score of 102
8.9.2.5 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, 
... 
[functions] [complex] [assumptions] [variable-definitions]
 
asked by Matthew Brunetti https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=22304 Score of 49
answered by SquareOne https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=19960 Score of 33
8.9.2.6 How can I plot the direction field for a differential equation?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=8841

I'd like to plot the graph of the direction field for a differential equation, to get a feel for it.  I'm a novice, right now, when it comes to plotting in Mathematica, so I'm hoping that someone can ... 
[plotting] [differential-equations]
 
asked by Matt Groff https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1735 Score of 36
answered by Peter Breitfeld https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=307 Score of 29
8.9.2.7 Creating a table/Matrix during a For loop

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=2930

I have a  For  loop (with  i  as a counter), which calculates different values ( y1 , ... 
[matrix]
 
asked by Solarboy https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=727 Score of 12
answered by Mr.Wizard https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=121 Score of 15