10.19.2 Greatest hits from previous weeks

10.19.2.1 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 Score of 32

answered by Hugh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12558 Score of 78

10.19.2.2 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 23

answered by J. M.'s missing motivation https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=50 Score of 17

10.19.2.3 Finding Limits in several variables

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=21544

Is there a way to find a limit of a multivariable function, like 
 
$$\lim_{(x,y)\to (0,0)} f(x,y)$$ 
with Mathematica? 
 
When $f$ is continuous, we can use 
$$\lim_{(x,y)\to (0,0)} f(x,y)=\lim_{(x,0)\... 
[functions] [calculus-and-analysis]
 

asked by Dominic Michaelis https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5899 Score of 34

answered by whuber https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=91 Score of 44

10.19.2.4 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 80

10.19.2.5 Find eigen energies of time-independent Schrödinger equation

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=32293

I'm trying to get the eigenvalues of a one dimensional time-independent Schrödinger equation, 
 
$-\frac{h^2}{2m_0}\frac{d^2\psi}{dx^2}+U(x)~\psi=Ei~\psi$ 
 
where U(x) is some potential and Ei is the ... 
[equation-solving] [physics] [parametric-functions]
 

asked by xslittlegrass https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1364 Score of 53

answered by Jens https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=245 Score of 48

10.19.2.6 Calling Correct Function for Plotting DiracDelta

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=3506

I am wondering what is the correct function in Mathematica to plot the true impulse function, better known as the  DiracDelta[]  function. When using this inside of a ... 
[plotting] [functions]
 

asked by night owl https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=116 Score of 19

answered by Heike https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=46 Score of 21

10.19.2.7 What is the difference between Reduce and Solve?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=17127

 Solve  and  Reduce  both can be used for solving equations. 
 
Just by working with them, I know there are some differences between ... 
[equation-solving] [functions] [function-comparison]
 

asked by lachis83 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=2371 Score of 114

answered by Artes https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=184 Score of 108