11.14.1 Top new questions this week

11.14.1.1 What chemical database does Mathematica use?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=312298

I am new in chemical part of Mathematica and do not know how it operates with molecules. I see, that Mathematica knows the geometry of many molecules. But where does it extract this geometry from? ... 
[chemistry]
 

asked by BazarovKV https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=107833 Score of 7

answered by Jason B. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9490 Score of 13

11.14.1.2 Heat equation, NeumannValue and RegionBoundary issues

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=312283

Context 
I am interested in solving (no outgoing flux) heat equations on non trivial region with a specific boundary condition. For simplicity I assume here a  Disk  ... 
[differential-equations] [finite-element-method] [heat-equation]
 

asked by chris https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1089 Score of 7

answered by user21 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=18437 Score of 4

11.14.1.3 Numbers which are not the sum of distinct squares

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=312252

A001422 gives the whole set of 31 numbers which are not the sum of distinct squares (see also MathWorld). That article also provides code for it: 
... 
[number-theory] [code-golf]
 

asked by Vitaliy Kaurov https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13 Score of 7

answered by vindobona https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=58868 Score of 5

11.14.1.4 How can I draw Union of two cylinders like this?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=312243

I am trying to draw this picture 
 
I tried 
 CSGRegion["Union", {Cylinder[{{-50, 0, 0}, {50, 0, 0}}, 20], Cylinder[{{0, -50, 0}, {0, 50, 0}}, 20]}] 
 
[graphics3d] [regions] [opencascade]
 

asked by minhthien_2016 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5320 Score of 6

answered by cvgmt https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72111 Score of 16

11.14.1.5 STL-file Contains Mesh Defects

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=312229

I want to make a piece of "curve object" for 3D printing. 
I made a mesh region using points along a curve and exported it to an STL-file. 
I verified the STL-file and found the result ... 
[export] [regions] [mesh] [stl] [3dprint]
 

asked by qwerty https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5861 Score of 6

answered by Greg Hurst https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4346 Score of 5

11.14.1.6 Solution for 5D integral in unit hypercube

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=312326

I need to find a closed form for $$\int_{(0,1)^5} \frac{x^3 (1-x)^3 y^3 (1-y)^2 z^6 u^2 v^3(1-v)^2}{(1-xyzuv)^3(1-xyzu)(1-xyz)^3(1-xy)} \; {\rm d}x \,{\rm d}y\,{\rm d}z\,{\rm d}u\,{\rm d}v$$ 
I am ... 
[calculus-and-analysis] [mathematica-online] [webmathematica]
 

asked by Max https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=91792 Score of 4

answered by Mariusz Iwaniuk https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=26828 Score of 6

11.14.1.7 Strange results about the sine function of a big integer

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=312329

I want to calculate the sine of a big integer, e.g., Sin[10^50], but found that N[Sin[10^50]], N[Sin[10^50],10], and N[Sin[10^50],20] give different results: 
... 
[numerics] [precision-and-accuracy] [machine-precision] [arbitrary-precision] [big-numbers]
 

asked by Quantum Physics https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=38775 Score of 4