11.29.2 Greatest hits from previous weeks

11.29.2.1 QR Code in shopping cart handle
11.29.2.2 Extract real part of a complex expression better than Re does
11.29.2.3 How to express trigonometric equation in terms of of given trigonometric function?
11.29.2.4 How to calculate scalar curvature, Ricci tensor and Christoffel symbols in Mathematica?
11.29.2.5 How can I plot implicit equations?
11.29.2.6 Get a "step-by-step" evaluation in Mathematica
11.29.2.7 How to make an inkblot?
11.29.2.1 QR Code in shopping cart handle

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=26268

This week, the market people from my work wanted to put QR codes in shopping cart handles, but when they tested it, the QR code did not work. I noted that the cylindrical curvature (even small) ... 
[image-processing]
 
asked by Murta https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=2266 Score of 203
answered by halirutan https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=187 Score of 197
11.29.2.2 Extract real part of a complex expression better than Re does

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=3306

I have a complex expression with real positive variables only. 
 
Mathematica Input Style: 
 
... 
[symbolic] [trigonometry]
 
asked by max https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=796 Score of 40
answered by nixeagle https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=814 Score of 62
11.29.2.3 How to express trigonometric equation in terms of of given trigonometric function?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=434

How can I express a trigonometric equation / identity in terms of a given trigonometric function? 
 
using following trigonometric identities 
 
... 
[functions] [trigonometry]
 
asked by Prashant Bhate https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=99 Score of 31
answered by Simon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=34 Score of 38
11.29.2.4 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
11.29.2.5 How can I plot implicit equations?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=34668

If you enter the following into Wolfram | Alpha, you get nice graphs: 
 
 graph 4 x^4 + y^2 = 2 
 
How do you do this in Mathmatica? I realize that these are not ... 
[plotting] [faq]
 
asked by Rollie https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=10174 Score of 44
answered by Timothy Wofford https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9391 Score of 47
11.29.2.6 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
11.29.2.7 How to make an inkblot?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=3345

How to effectively create a polygon that looks like a realistic inkblot? So far, I could come up with this (borrowing from Ed Pegg Jr.'s Rorschach demonstration): 
 
... 
[graphics] [performance-tuning] [image-processing] [generative-art]
 
asked by István Zachar https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89 Score of 92
answered by Sjoerd C. de Vries https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=57 Score of 56