2.3.2 Greatest hits from previous weeks

2.3.2.1 Why is raytracing so slow?
2.3.2.2 Generate a Unit Circle Trigonometry
2.3.2.3 Drawing a square root spiral
2.3.2.4 How do I make a 3DPlot using cylindrical coordinates?
2.3.2.5 How to calculate contour integrals with Mathematica?
2.3.2.6 Skip header lines on import
2.3.2.7 Using Export[] sends the file where?
2.3.2.8 Can you answer these questions
2.3.2.9 Periodical sum of rows by a certain step
2.3.2.10 Behavior of $MinPrecision seems to have changed between 12.0.0 and 12.1.1
2.3.2.11 HankelTransform problem
2.3.2.1 Why is raytracing so slow?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=219629

I’m trying to get some rays to bounce in a circle. But I want to be able to control the reflections, i.e. the direction the rays bounce in the circle. I have a MWE below, and it is severely limited by ...

asked by Tomi https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=36939 31 votes

answered by Tim Laska https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=61809 42 votes

2.3.2.2 Generate a Unit Circle Trigonometry

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=2456

Struggling often with Trigonometry I would like to have some code to generate this Unit Circle Trigonometry. Would be of great help when I need to transform some data :

asked by 500 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=172 18 votes

answered by Mark McClure https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=36 32 votes

2.3.2.3 Drawing a square root spiral

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=66969

Here is a start. I’m looking for a nice way to draw it.

asked by matrix89 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5379 24 votes

answered by Bob Hanlon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9362 21 votes

2.3.2.4 How do I make a 3DPlot 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 ...

asked by Learning is a mess https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5643 18 votes

answered by whuber https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=91 24 votes

2.3.2.5 How to calculate contour integrals with Mathematica?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=34073

How to calculate the integral of \(\frac {1}{\sqrt {4 z^2 + 4 z + 3}}\) over the unit circle counterclockwise for each branch of the integrand?

asked by user64494 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7152 42 votes

answered by Artes https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=184 64 votes

2.3.2.6 Skip header lines on import

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=50718

When importing a data file what are the comment symbols for Mathematica? That is, given a file like this

blabla 
bulbul 
 
1 2 6 54 7 ...

what symbol do I have ...

asked by MaxJ https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=14687 20 votes

answered by george2079 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=2079 18 votes

2.3.2.7 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 ...

asked by Patrick Da Silva https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1785 37 votes

answered by Vitaliy Kaurov https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13 51 votes

2.3.2.8 Can you answer these questions
2.3.2.9 Periodical sum of rows by a certain step

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=236085

I’ve been struggling with one problem. I have a classic matrix in this example 12x4 such as: matrix = Table[i, {i, 12}, {4}]

asked by Jakub Petrj https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=75456 2 votes

answered by Carl Woll https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=45431 0 votes

2.3.2.10 Behavior of $MinPrecision seems to have changed between 12.0.0 and 12.1.1

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=235851

I am running into a very weird bug where setting $MinPrecisionto some value (in this case 200 has a very different and ...

asked by Kvothe https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=45020 3 votes

2.3.2.11 HankelTransform problem

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=236119

Somewhere in the following code there is a bug. The result should not be zero! FunctionExpand@HankelTransform[Sqrt[r] Cos[r], r, k, 1/2]

I think the answer should ...

asked by SolutionExists https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70331 1 vote