9.21.3 Can you answer these questions?

9.21.3.1 Reveal details in contour and density plots

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=286826

We numerically solve for the electric potential on a box  which obeys Ohm's law: 
\begin{equation}\nabla\cdot(\overset{\scriptscriptstyle\leftrightarrow}{\sigma} \nabla \Phi) = 0, \label{Eqn:OhmsLaw}\... 
[plotting] [differential-equations] [finite-element-method]
 

asked by Charlie https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=85247 Score of 1

answered by Ulrich Neumann https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53677 Score of 0

9.21.3.2 Communicating with USB device

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=286587

I would like to control and acquire data from a USB device using MMA 13 running on Windows 10. (The device is an Ocean Optics HR2000 spectrometer.) I Do not have a device driver or an API for the ... 
[input-devices]
 

asked by David Keith https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=44700 Score of 1

9.21.3.3 Finding Petrov type of a metric

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=286745

Is there a subpackage in xAct (or another Mathematica package for general relativity calculations) to determine the Petrov type of a metric? 
I understand that xAct has a lot of subpackages for ... 
[tensors] [xact]
 

asked by stupidstudent https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89184 Score of 1