# All Questions

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18 views

### How to implement a frequency domain filter in python [closed]

Im trying to implement a frequency-domain filter in python using an specific response function. The idea is to perform the Fourier transform of an image multiply it by the filter response function and ...
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### Weak form of the Navier-Cauchy equation

I am trying to obtain the weak form of the Navier-Cauchy equation, which is $$- \rho \omega ^2 \textbf{U} - \mu \nabla ^2 \textbf{U} - (\mu + \lambda) \nabla (\nabla \cdot \textbf{U}) = \textbf{F}$$ ...
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### Python Environment Carrying Over to Jobs

I am trying to run a software package developed that has some dependencies such as numpy on a cluster. My issue seems to be with the python environment. I have set up the environment correctly for ...
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### FEM with elastic inhomogeneous properties leads to mesh-induced anisotropy

I'm solving an elastic homogenization problem and I'm having problems with mesh artifacts. I would like to first give a brief summary of what I do: I have a system with inhomogeneous (but isotropic) ...
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### Issue solving nonlinear equation containing a quotient

I have a coupled set of PDEs that need to be solved as part of a larger problem. I am currently approaching this by computing spatial derivatives with finite differences and using PETSc's nonlinear ...
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### Efficient way to solve a set of linear equations Ax=b when A is sparse and some elements of b are equal to zero

I have a set of linear equations, Ax=b. And about half of the elements in the right hand side (vector 'b') are equal to zero. My system matrix 'A' is a sparse complex matrix. And 'A' is in the size ...
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### Effect on methods like Crank-Nicolson of adding a potential term, changing heat equation to Schrodinger equation

I'm studying up on methods for numerically solving the Schrodinger equation. The Schrodinger equation with a zero potential is formally identical to the heat equation in the sense that we just make ...
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### Euler Explict Method for solving the PDE for option prices under the Schwartz mean reverting model. Numerical Finance

I have to solve the following PDE for a Call option : $\partial_tV + \{ \alpha - (\mu - \lambda/ \alpha -log(S))\}S\partial_SV + 1/2 \sigma^{2}S^{2}\partial_{S}^{2}V - rV = 0$ Where V(S,t) is the ...
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### Solver for large dense BVP system in python

I have a large system of boundary value problems of the form $$\frac{d^2 y }{dt^2} = C(t) y + b(t),$$ where the variable $y$ is a vector that has anywhere from 50 to around 500 components, $C$ is a ...
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### C++: function calling order (inheritnce and methods) [closed]

I was asked to write the output of this code: ...
26 views

### How property-invariance is imposed to neural nets?

I was wondering how specific symmetries or constraints such as property-invariance transformation are imposed on any (deep) neural net when they are trained. I'll appreciate it if anyone can aware me ...
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### Cell-centered DG extension to the two-point flux approximation scheme

A current problem that I am working on requires me to compute the solution from the heat diffusion evolution on a discontinuous function. More precisely - I have a Delaunay triangulation and within ...
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### Compute Nullspace of Sparse Matrix

I am computing the nullspace of a sparse rectangular $m$ x $n$ matrix $A$, where $m$ << $n$. I do this by computing the QR decomposition of $A^T$ and extract the $n-m$ right-most columns of the ...
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### Applying the result of Cuthill-McKee in SciPy (followup)

This is a followup to Applying the result of Cuthill-McKee in SciPy , where I'm not sure the answer given is correct. It's also 4 years old, so I'm trying a new question. The question is still ...
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### Problem with physical groups to label surface in GMSH

I'm having some troubles setting the ID for the physical group of the boundary and then extract them later in Python. Here's my main.geo file: ...
I'm sure this question has been asked before yet after many hours of searching I am unable to find a definitive answer. The problem at hand is solving the linear system: $$A \mathbf{x} = \mathbf{0}$$ ...