12.14.2 Greatest hits from previous weeks

12.14.2.1 How to calculate scalar curvature, Ricci tensor and Christoffel symbols in Mathematica?
12.14.2.2 How do I make a plot using cylindrical coordinates?
12.14.2.3 How to add a vertical line to a plot?
12.14.2.4 Why should I avoid the For loop in Mathematica?
12.14.2.5 Calculating the normalization constant for a wavefunction
12.14.2.6 Plotting a Phase Portrait
12.14.2.7 How to perform a multi-peak fitting?
12.14.2.1 How to calculate scalar curvature, Ricci tensor and Christoffel symbols in Mathematica?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=8895

I am seeking a convenient and effective way to calculate such geometric quantities. I've used packages like  TensoriaCalc , but they don't work at all time. Sometimes,... 
[symbolic] [physics] [tensors] [differential-geometry]
 
asked by Zoe Rowa https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1713 Score of 54
answered by Yi-Zen Chu https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4869 Score of 26
12.14.2.2 How do I make a plot using cylindrical coordinates?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=19076

I'm trying to plot a function of the form $z(r,\theta)$ where $r \in [0, R]$ for a finite R, $\theta \in [0,2\pi[$, and z is the third coordinate, a function of the first two. I couldn't find anything ... 
[plotting]
 
asked by Learning is a mess https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5643 Score of 21
answered by whuber https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=91 Score of 33
12.14.2.3 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? 
 
... 
[plotting]
 
asked by sjdh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=515 Score of 89
answered by Ajasja https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=745 Score of 104
12.14.2.4 Why should I avoid the For loop in Mathematica?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=134609

Some people advise against the use of  For  loops in Mathematica. Why?  Should I heed this advice?  What is wrong with  For ?  What ... 
[core-language] [coding-style] [faq]
 
asked by Szabolcs https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12 Score of 120
answered by Szabolcs https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12 Score of 128
12.14.2.5 Calculating the normalization constant for a wavefunction

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=99248

How can I compute the normalization constant for a quantum mechanics wave-function, like $\Psi(x) = N \exp(-\lambda x^2/2)$ by using Mathematica? (The normalization constant is $N$). 
[physics]
 
asked by infiniteNOP https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=35524 Score of 2
answered by Jason B. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9490 Score of 5
12.14.2.6 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
12.14.2.7 How to perform a multi-peak fitting?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=26336

I am wondering how to implement the multi-peak detecting and fitting in Mathematica. Following is an example of fitting the data using three peaks (such that the data ~ peak1 + peak2 + peak3). 
The ... 
[fitting] [data] [peak-detection]
 
asked by Everett You https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1389 Score of 58
answered by Silvia https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=17 Score of 57