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### Reveal the formal PDE of FiniteElement

When FiniteElement method is used, the differential equations will first be transformed to certain standard form (named as formal PDE in recent FEM document), and ...
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### How to use Finite elements to solve an initial value ODE with NDSolve?

This is on 11.3, windows 7 I have not used Mathematica FEM much at all. So sorry for this basic question on using it to solve a basic second order initial value ODE. I want to use ...
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339 views

### Counterpart of Maple's LSSolve in Mathematica

I am a great fan of Mathematica. Unfortunately, due to some specific tasks I had to move to Maple. I think it's my lack of info that is not letting me do those tasks. That is why I am asking some ...
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939 views

### Laplace equation with robin boundary conditions

I want to solve the following steady state heat transfer problem with robin boundary condition at the bottom: The following is the code for the transient solution, but how should I change the code ...
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### PDE solving for two different regions?

I have searched and read all previous questions but cannot get my head around this. I am new to mathematica. I have two regions in 2D where I want to solve PDE. Of the form: ...
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### why Mathematica gives zero as eigenvalue for $y''+\lambda y=0$ for these boundary conditions?

I was trying to verify my hand solution using Mathematica for this problem $$y^{\prime\prime}+\lambda y=0$$ The domain is $0<x<L$ and the boundary conditions are \begin{align*} y(0)+...
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203 views

### Convert boundary condition involving derivative to NeumannValue programmatically

As discussed in e.g. what causes the error "The dependent variable in the boundary condition needs to be linear" when using NDSolve? When FiniteElement ...
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229 views

### Variation of the biharmonic equation with Neumann conditions

I am currently writing a script to plot the solution of a variant of the biharmonic equation. In this case the equation I want to solve is ...
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274 views

### Solving a coupled PDEs using FEM with Robin conditions

The same type of question has been answered here but for single PDE. The main issue I am facing is how to write the weak form for two PDEs. \epsilon^2\frac{\partial ^2u}{\partial x^2}+\frac{\...
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