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76 views

How to subtract two non-closed surfaces from each other in VTK or ParaView?

I'm trying to subtract two surfaces, which are shown below in this image, by using VTK or ParaView. I'm aware of vtkBooleanOperationPolyDataFilter but that filter needs its inputs to be closed ...
39 views

Access PETSc data in totalview?

Is it possible to view the data stored in the various PETSc data types from within totalview? Ordinarily, PETSc types are integers which act as pointers to the actual data (obviously my understanding ...
15 views

How to choose metrics for evaluating classification results?

Recently we have developed a python library named PyCM specialized for analyzing multi-class confusion matrices. A parameter recommender system has been added in version 1.9 of this module in order ...
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OpenCV: How to get the “rectified” fundamental matrix?

I have a stereo image pair and the respective intrinsics and extrinsics of both cameras. With this information, I can calculate the fundamental Matrix between the two cameras (let's call it F). I can ...
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How does one do electrodynamics simulations in SU2?

The description of SU2 says The primary applications are computational fluid dynamics and aerodynamic shape optimization, but has been extended to treat more general equations such as ...
51 views

Simplification of an optimization objective

Let $G(V,E)$ is a weighted simple graph, where $V$ and $E$ are the set of vertices and Edges. The graph is undirected. Let $A \in \{0,1\}^{n\times n}$ and $W \in R_+^{n\times n}$ be the adjacency ...
36 views

Open Source Packages Implementing Continuous Wavelet and Scaling Functions

I'm looking for an open source software package that provides a fast evaluation of continuous Daubechies/Symmlet wavelet/scaling functions. GSL only has the discrete wavelets, and PyWavelets comes ...
32 views

Compute a Boltzman partition function

I'm trying to calculate total energy of a system $$E(v, h) = -\sum a_iv_i - \sum b_jh_j - \sum_{i,j} v_ih_jw_{ij}$$ Python equivalent looks like this ...
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What's a time centered Riemann problem?

I am trying to understand the meshless methods as described in https://arxiv.org/pdf/1409.7395.pdf. I'm having trouble understanding the following step: (Page 7, just after equation 17) Now, rather ...
79 views

why I cannot find explicit finite difference for elliptic equation

Let us think on the Poisson equation $\nabla^2 u(\bf{x})=\rho(x)$ with Neumann boundary conditions, with $\bf{x}=\it (x,y)$ in 2D. Here is a stencil with central differences in both $x$ and $y$ (...
126 views

Converting ROOT Tree to HDF5

I have a TTree in ROOT with 1000 events and 15 variables associated to each of them. I would like to convert this in its entirety to an hdf5 dataset. How do I organise my data in HDF5 Groups such that ...
37 views

R function or package for carrying out maximum likelihood techniques in random effect models

I am applying optim() function in R to obtain maximum likelihood estimates of the fixed effects and random effects in a model with bivariate random effects. The ...
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temperature profile on axial direction of a chamber

I have a task to plot average temperature profile at each cross-section in the axial direction of a combustion chamber. I have $x$, $y$, $z$ coordinates data in excel as well as the corresponding ...
53 views

Does radioisotope decay affect computer systems?

It is known that there exist a number of radioisotopes of elements commonly used in computer systems. Is the decay of these materials known to affect device performance over time, or is its impact so ...
467 views

Finite Element Analysis for Laminated Plates with Holes or Patches

As the title says, I am trying to code in FEM a plate structure that either has a hole in one of the layers or one of the layers is made of patches of plates, rather than one whole plate. However, ...
261 views

Boundary conditions for streamlines in enclosed flow

I am trying to solve Lid driven square cavity flow problem of Stokes equation using finite element method. I have boundary conditions for velocity as zeros on every boundary but u=1 on top boundary. ...
315 views

Imposing total pressure over surface in FEM

I am trying to solve Stokes problem using Finite element method. My question is how to impose that total pressure over the surface is zero to remove the constant pressure mode?
323 views

Stability of nonlinear partial differential equation

I want to find an expression for the stability of the nonlinear Poisson equation. I know about von Neumann stability analysis which applies to linear equations as far as I know. Any suggestion how to ...
633 views

Tridiagonal Solver in Python

I have a code I'm working on that involves solving a 1D Schrodinger equation using a Crank-Nicolson time step. The code is written in NumPy/SciPy, and I was doing a bit of profiling and discovered ...
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3D Diffusion Equation in Fourier space

I'm solving the 3D Diffusion equation $$u_t=k(u_{xx}+u_{yy}+u_{zz})$$ in MATLAB using Fourier techniques. I assume a 3D Fourier expansion $(e^{-ipx},e^{-imy},e^{-imz})$of the solution. Physical ...
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Order of accuracy of linearised vs non-linear system

Does the order of accuracy of a combination of schemes applied to solve a system of non-linear equations, match those of the same schemes applied to the linearised version of the system? In other ...
256 views

Cholesky factorization of a block matrix

Let a Matrix $\mathbf{Y=[A\;b;b^T\;}d]$, where $d$ is a scalar, and $\mathbf{b}$ is a vector. How to find the cholesky factorization of $\mathbf{Y}$ if i know the cholesky factorization of $\mathbf{A}$...
45 views

comparison of stability of two non-linear methods

I have solved a numerical problem using two different sets of non-linear governing equations. I want to get an understanding of the stability of the methods relative to each other. To do so, I solving ...
I have given $i_1$, $i_2$ and $\alpha$ which can be real or integer. How can I find the roots of: $$(i_1 + i_p )^{\alpha} - i_p^{\alpha} - (i_2 \cdot i_p^{\alpha-1}) = 0$$