10.40.1 Top new questions this week

10.40.1.1 FiniteElement method cannot handle $\frac \partial^2 u  \partial x \partial y =1$ well?
10.40.1.2 NIntegrate doesn't calculate a triple integral
10.40.1.3 Dynamic movement of a circle and resulting ratio of intersecting areas
10.40.1.4 Map or Thread operation for list
10.40.1.5 From exponent of sum to product of exponents
10.40.1.6 How can I numerically solve this trigonometric equation?
10.40.1.7 Interpretation + Information leads to infinite recursion
10.40.1.1 FiniteElement method cannot handle $\frac \partial^2 u  \partial x \partial y =1$ well?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=309065

Consider this toy example: 
$$\newcommand{\p}{\partial}\newcommand{\f}{\frac} 
\left\{\begin{array}{l}\f{\p^2 u}{\p x \p y}=1\\ 
\left.u\right|_{x=0}=0\\ 
\left.u\right|_{y=0}=0\end{array}\right.$$ 
... 
[differential-equations] [finite-element-method]
 
asked by xzczd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1871 Score of 12
answered by Alex Trounev https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=58388 Score of 8
10.40.1.2 NIntegrate doesn't calculate a triple integral

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=309130

I have an integral of dubious origin, which I don't know how to calculate: 
... 
[calculus-and-analysis] [numerical-integration]
 
asked by Monster https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=80016 Score of 5
answered by user64494 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7152 Score of 3
10.40.1.3 Dynamic movement of a circle and resulting ratio of intersecting areas

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=309027

We have 3 circles. The middle one has to move along the line y=-x towards the top left such that the resulting area of the respective intersecting regions become 4:1 
I have below thus far to just ... 
[graphics] [area]
 
asked by Steve237 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=69429 Score of 5
answered by ydd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72953 Score of 6
10.40.1.4 Map or Thread operation for list

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=308960

I have data such as 
... 
[list-manipulation]
 
asked by rani https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89293 Score of 5
answered by Michael E2 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4999 Score of 6
10.40.1.5 From exponent of sum to product of exponents

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=308986

Good day 
I have an expression 
 Exp[m I (a (Exp[-I x] + Exp[+I x]) + b (Exp[-3 I x] + Exp[+3 I x]))] 
 
I want to convince Mathematica to expand the exponent, 
... 
[simplifying-expressions] [expression-manipulation]
 
asked by Boudewijn Verhaar https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=88975 Score of 5
answered by Syed https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=81335 Score of 5
10.40.1.6 How can I numerically solve this trigonometric equation?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=309117

I have tried to use the following. 
 NSolve[Cos[Pi/2*Cos[\[Theta]]]/Sin[\[Theta]] == 1/Sqrt[2], \[Theta]] 
 
However, I have this error. 
NSolve::nsmet: This system ... 
[equation-solving]
 
asked by kile https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=65814 Score of 4
answered by Michael E2 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4999 Score of 5
10.40.1.7 Interpretation + Information leads to infinite recursion

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=309126

It looks like a bug, or am I using  Interpretation  incorrectly? 
Any workaround? 
Example 
First, we give the following definition so that ... 
[formatting] [front-end] [boxes]
 
asked by Lacia https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=86893 Score of 4