8.17.2 Greatest hits from previous weeks

8.17.2.1 How do I identify the source of a "Tag times protected" error?
8.17.2.2 Find eigen energies of time-independent Schrödinger equation
8.17.2.3 Mathematica Minecraft
8.17.2.4 Smiley Face using parametric equations
8.17.2.5 Why I get the "Set::write: "Tag Times in is Protected." error?
8.17.2.6 What is the equation to plot a vertical line?
8.17.2.7 How to make Jacobian automatically in Mathematica
8.17.2.1 How do I identify the source of a "Tag times protected" error?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=11982

I have some code that looks like 
 
 Table[ 
a = 1; 
b = {2, 3} 
c = i;, 
{i, 2} 
] 
 
 
which gives an error: 
Set::write: Tag Times in c {2,3} is Protected.... 
[warning-messages] [syntax] [debugging] [faq]
 
asked by dearN https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=204 Score of 31
answered by Mr.Wizard https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=121 Score of 37
8.17.2.2 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 50
answered by Jens https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=245 Score of 46
8.17.2.3 Mathematica Minecraft

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=19669

Some time ago I asked myself: with all these great graphics and interactive capabilities of Mathematica, what kinds of 3D games can be implemented in it?  And the answer which came to mind is ... 
[programming] [dynamic] [graphics3d] [eventhandler] [development]
 
asked by faleichik https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=219 Score of 169
answered by faleichik https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=219 Score of 247
8.17.2.4 Smiley Face using parametric equations

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=137669

I need to know the parametric equations for this smiley face and how to draw it in Mathematica.  I'm completely lost. 
[plotting] [parametric-functions] [homework]
 
asked by Woeseph https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=46575 Score of 1
answered by Bob Hanlon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9362 Score of 5
8.17.2.5 Why I get the "Set::write: "Tag Times in is Protected." error?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=11868

Why I get the error below with this code: 
 
... 
[vector-calculus]
 
asked by Aurelius https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1669 Score of 10
answered by Mark McClure https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=36 Score of 13
8.17.2.6 What is the equation to plot a vertical line?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=59476

Please help. Trying to find area between three curves,  e^-x, x = 2, y = 1 . Can't find out how to plot  x = 2 . Don't want to use <... 
[plotting] [calculus-and-analysis]
 
asked by Cory https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=19717 Score of 6
answered by Basheer Algohi https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13548 Score of 12
8.17.2.7 How to make Jacobian automatically in Mathematica

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=5790

If we have two vectors, $a$ and $b$, how can I make Jacobian matrix automatically in Mathematica? 
 
$$ a=\left( 
\begin{array}{c} 
x_1^3+2x_2^2 \\ 
3x_1^4+7x_2 
\end{array} 
\right);b=\left( 
\begin{array}{... 
[vector-calculus]
 
asked by George Mills https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1012 Score of 41
answered by Jens https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=245 Score of 57