Computational Science Stack Exchange
Computational Science Stack Exchange

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What is the correct way of integrating in astronomy simulations?

I'm creating a simple astronomy simulator that should use Newtonian physics to simulate movement of planets in a system (or any objects, for that matter). All the bodies are circles in an Euclidean plane, that have properties such as position,…
jcora
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What would be the most helpful way to write code for a paper so that readers can clearly match the results to the code that generates them?

I'm writing a reproducible paper, and the paper has computational results that are generated by a Python script (a similar MATLAB script generates nearly identical results). I feel that the paper would be easier to understand for readers if they…
Geoff Oxberry
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What is the current state of polynomial preconditioners?

I wonder what has happened to polynomial preconditioners. I am interested in them, because they appear to be comparatively elegant from a mathematical perspective, but as far as I have read in surveys on krylov methods, they generally perform very…
shuhalo
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What guidelines should I follow for simulation software projects?

I am not sure whether this question belongs here, but I would like to give it a try and benefit from the experience of the people at scicomp.SE. From my experience, the software quality in computational science often leaves a bit to be desired.…
carlosvalderrama
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How do low rank modifications affect Krylov method convergence?

Say I have a linear system $A x = b$, which converges quickly using a suitable Krylov method (such as CG or GMRES) for all $b$. If $B$ is a matrix with low rank $r$, will the same Krylov method on the system $(A + B) x = b$ also converge quickly…
Geoffrey Irving
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Why does the numerical solution of an ODE move away from an unstable equilibrium?

I wish to simulate the behaviour of a double-pendulum-like system. The system is a 2-degrees-of-freedom robot manipulator that is not actuated and will, therefore, behave mostly like a double-pendulum affected by gravity. The only main difference…
Meclassic
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Visualizing discontinuous Galerkin/finite element data

I would like to visualize simulation results, obtained using the discontinuous Galerkin (DG) approach, within ParaView. Similarly to finite volume methods, the problem domain is divided into cube-shaped cells ("elements"). As opposed to finite…
Michael Schlottke-Lakemper
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Testing numerical optimization methods: Rosenbrock vs. real test functions

There seem to be two main kinds of test function for no-derivative optimizers: one-liners like the Rosenbrock function ff., with start points sets of real data points, with an interpolator Is it possible to compare say 10d Rosenbrock with any…
denis
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Design patterns in writing numerical software in C++

I'm looking for resources on design patterns and principles for numerical software, potentially but not necessarily with a focus on object-oriented approaches to numerical codes. I am aware of the text, Writing Scientific Software: A Guide for Good…
user1997744
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How to deal with too much data?

Our plasma dynamics simulations often produce too much information. During the simulations we record various physical properties on a grid (x,y,z,t) that is as large as (8192x1024x1024x1500), for at least 10 properties. This information is processed…
Yann
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How to start using LAPACK in c++?

I'm new to computational science and I already have learned basic methods for integration, interpolation, methods like RK4, Numerov etc on c++ but recently my professor asked me to learn how to use LAPACK for solving problems related to matrices.…
Alireza
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Finding which triangles points are in

Suppose I have a 2D mesh consisting of nonoverlapping triangles $\{T_k\}_{k=1}^N$, and a set of points $\{p_i\}_{i=1}^M \subset \cup_{k=1}^N T_K$. What is the best way to determine which triangle each of the points lies in? For example, in the…
Nick Alger
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Fitting Implicit Surfaces to Oriented Point Sets

I have a question regarding quadric fit to a set of points and corresponding normals (or equivalently, tangents). Fitting quadric surfaces to point data is well explored. Some works are as follows: Type-Constrained Direct Fitting of Quadric…
Tolga Birdal
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How to numerically calculate residues?

I need to calculate the following integral: $$ {1\over 2\pi i} \int_C f(E) \, d E $$ $$ f(E) = {\rm Tr}\,\left(({\bf h} + E)\,{\bf G}(E) \right) $$ Where $\bf h$ is a matrix (one particle kinetic and potential energy expressed in a basis), $\bf G$…
Ondřej Čertík
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Scientific Programming Contests

I regularly compete in so called "Programming Contests", where you solve difficult algorithmic problems with your own code and problem solving skills during a limited time-frame. For referential examples of what those might look like, search for…
MonadBoy
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