11.44.2 Greatest hits from previous weeks

11.44.2.1 How do I plot a plane EM wave?
11.44.2.2 Plotting a Phase Portrait
11.44.2.3 Get a "step-by-step" evaluation in Mathematica
11.44.2.4 How can I transpose x and y axis on a Plot?
11.44.2.5 What does "Tag Integer is Protected" message mean?
11.44.2.6 Make a scatter plot from two lists
11.44.2.7 Using Export[] sends the file where?
11.44.2.1 How do I plot a plane EM wave?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=1987

I would like to display an electromagnetic (EM) wave.  I have written code that works, but it does not "shade" the area between the graph and the axes.  Both the ... 
[graphics] [physics] [visualization]
 
asked by Rainforest Frog https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=202 Score of 25
answered by J. M.'s missing motivation https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=50 Score of 18
11.44.2.2 Plotting a Phase Portrait

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=14160

I'm trying to plot a phase portrait for the differential equation 
$$x'' - (1 - x^2) x' + x = 0.5 \cos(1.1 t)\,.$$ 
The primes are derivatives with respect to $t$. I've reduced this second order ODE to ... 
[plotting] [differential-equations]
 
asked by covertbob https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4528 Score of 48
answered by David Slater https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1746 Score of 42
11.44.2.3 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 Score of 149
answered by J. M.'s missing motivation https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=50 Score of 122
11.44.2.4 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 20
11.44.2.5 What does "Tag Integer is Protected" message mean?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=6738

(Newbie question) 
 
For every function I define I get this message: 
When I close and reopen Mathematica, and re-enter the function definition, I don't get the message anymore. What does it mean? 
[warning-messages]
 
asked by stevenvh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1450 Score of 16
answered by J. M.'s missing motivation https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=50 Score of 17
11.44.2.6 Make a scatter plot from two lists

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=21884

I have two lists of values 
 
 xx = {0.1, 0.3, 0.35, 0.57, 0.88, 1.0} 
yy = {1.2, 3.5, 4.5, 7.8, 9.0, 12.2} 
 
 
I want to make a scatter plot (list plot) with xx as x ... 
[plotting]
 
asked by JACKY88 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=2403 Score of 32
answered by Eric Thewalt https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=6313 Score of 47
11.44.2.7 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 ... 
[export]
 
asked by Patrick Da Silva https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1785 Score of 51
answered by Vitaliy Kaurov https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13 Score of 62