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# Computational Science : Recent Questions and Answers

## Why is Time evolving block decimation so efficient?

I have a short question about Time evolving block decimation (TEBD). During a lecture I was told that this method is very efficient in evolving 1D quantum...

## Optimization of expensive model with many parameters

I have a physical model which takes $sim50$ parameters and gives $sim2000$ outputs taking tens of minutes to run. I need to optimize these parameters to give outputs...

## Pros of Fourier-Galerkin spectral methods

What are the pros of Fourier-Galerkin spectral methods while solving PDEs? Here's the one that came in my mind first:Easy implementation: using this method, differentiation operator computation is really simple...

## Flux sign and face normal confusion in finite volume method

I implemented a solver for the 2D steady-state heat equation (without heat generation and homogeneous material) $nabla. (knabla T) = 0$, using finite volume method, however, I am having...

## Reading VTK file into C++ for analysis

I apologize in advance if this post is at all ignorant or elementary, I am a pure mathematician who is newly getting into the world of scientific computing. For my...

## Project to nearest point on convex polyhedron

I have a point $y in mathbb{R}^d$ and a convex polyhedron $mathcal{P}$ given as the intersection of half-spaces: mathcal{P} = {x in mathbb{R}^d mid a_1 cdot x...

## In FEM, why is the stiffness matrix positive definite?

In FEM classes, it's usually taken for granted that the stiffness matrix is positive definite, but I just can't understand why. Could anyone give some explanation? For instance, we can...

## debugging a rotation matrix for elastic constants

I have a transformation matrix which takes in the elastic constants from the local $rtl$ coordinates and then converts the elastic constants to the global $xyz$ coordinates via a rotation...

## Maximum lossless compression ratio for floating point time series

I want to compress an array of time series floating point data as much as possible. Currently the only algorithm I've found for this is XOR compression which works well,...

## Are there any embarrassingly parallel tasks that require a CPU rather than GPU?

I am looking for tasks thatare unsuitable for GPUsgain significant speedup as more CPU nodes are addeddon't require large data transfer or inter-thread communication between nodes.Do any problems of this...