7.26.2 Greatest hits from previous weeks

7.26.2.1 Selecting every n-th element from a list

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=64003

I have a list: 
 
 data = {4, 5, 7, 8, 9, 5, 3, 2, 1, 2, 13, 12}; 
 
 
I want to take those elements in the list which are located at equal distances, say, every third ... 
[list-manipulation] [filtering]
 

asked by Suro https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=20003 37 votes

answered by Szabolcs https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12 34 votes

7.26.2.2 What's the most difficult multidimensional integral that Mathematica has solved?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=222184

I am interested in benchmarking numerical integration methods and am trying to develop a wider set of difficult multivariate examples. For my particular methods, I only want to look at non-negative-... 
[calculus-and-analysis] [numerical-integration]
 

asked by ben18785 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=19278 6 votes

7.26.2.3 Mathematica vs. Python - how does Mathematica compare to Python's scientific computing suite?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=86058

Python's family of packages for scientific computing has matured rapidly. I can pretty much replicate all of Mathematica's functionalities, but with production level and open-source code using the ... 
[python] [system-performance]
 

asked by M.R. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=403 58 votes

answered by Jens https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=245 38 votes

7.26.2.4 Why am I getting that $0.999999999999988 \geq 1.0$ is True?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=241791

I am getting these results: 
... 
[numerics] [precision-and-accuracy]
 

asked by Craig Carter https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12461 22 votes

answered by Chip Hurst https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4346 24 votes

7.26.2.5 Finding unit tangent, normal, and binormal vectors for a given r(t)

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=18598

For my Calc III class, I need to find $T(t), N(t)$, and $B(t)$ for $t=1, 2$, and $-1$, given $r(t)=\{t,t^2,t^3\}$. 
 
I've got Mathematica, but I've never used it before and I'm not sure how to coerce ... 
[equation-solving] [calculus-and-analysis] [geometry] [vector-calculus] [homework]
 

asked by a98 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5605 32 votes

answered by Artes https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=184 46 votes

7.26.2.6 Can Mathematica do symbolic linear algebra?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=3242

For instance, is there some way I can say "let A and B be arbitrary real $m\times n$ and $k\times m$ matrices,  Simplify[Transpose[Transpose[A].Transpose[B]]] " and ... 
[linear-algebra] [symbolic]
 

asked by Niki Estner https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=242 65 votes

answered by Chip Hurst https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4346 10 votes

7.26.2.7 How to graph a sphere with cartesian equations?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=24169

I'm new to Mathematica and I need to ask how to graph a sphere, cylinder, etc.. using cartesian equations. 
 
For example in sphere's case $x^2+y^2+z^2=1$ 
 
I tried to use ... 
[plotting]
 

asked by German https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7145 8 votes

answered by Dr. belisarius https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=193 14 votes