Computational Science Stack Exchange
Computational Science Stack Exchange

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Python vs FORTRAN

Which one is better: FORTRAN or Python? And I guess that in both cases you need Gnuplot, am I right? I'm working on a Windows machine at the moment. I'd like to use it to get numerical solutions for physics-problems, including Monte-Carlo…
Nick
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Is there a general-purpose library for structured grid adaptive mesh refinement?

Adaptive mesh refinement (AMR) is a common technique for dealing with the problem of widely varying spatial scales in the numerical solution of PDEs. What general-purpose libraries exist for AMR on structured grids? Ideally I'd like something in…
David Ketcheson
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Euclidean distance in Octave

I would like to know if there is a quick way to compute the Euclidean distance of two vectors in Octave. It seems that there is no special function for that, so should I just use the formula with sqrt?
Mouna
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Problems where Conjugate gradient works much better than GMRES

I am interested in cases where Conjugate gradient works much better than GMRES method. In general, CG is preferable choice in many cases of SPD (symmetric-positive-definite) because it requires less storage and theoretical bound on convergence rate…
arbitUser1401
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What is the best way to do reproducible research if you need proprietary libraries?

Reproducible research in computation aims to make the code needed to generate the results in a computational paper available to other researchers so that they can run this code to reproduce the results in that paper. I'd like to make all of my…
Geoff Oxberry
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How to derive the Weak Formulation of a Partial Differential Equation for Finite Element Method?

I have taken a basic introduction to Finite Element Method, which did not emphasize a sophisticated understanding of a 'weak formulation'. I understand that with the galerkin method, we multiply both sides of the (elliptical) PDE by a test function…
Paul
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State of the Mac OS in Scientific Computing and HPC

Back towards the dawn of OS X, there seemed to be a great deal of hubbub, at least in the Mac world (I was nowhere near scientific computing at the time) about the Mac OS as a platform for scientific computing and HPC applications. XGrid came out of…
Fomite
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What is the advantage of multigrid over domain decomposition preconditioners, and vice versa?

This is mostly aimed for elliptic PDEs over convex domains, so that I can get a good overview of the two methods.
Jungho Lee
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Writing the Poisson equation finite-difference matrix with Neumann boundary conditions

I am interested in solving the Poisson equation using the finite-difference approach. I would like to better understand how to write the matrix equation with Neumann boundary conditions. Would someone review the following, is it correct? The…
boyfarrell
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Row major versus Column major layout of matrices

In programming dense matrix computations, is there any reason to choose a row-major layout of the over the column-major layout? I know that depending on the layout of the matrix chosen, we need to write the appropriate code to use the cache memories…
smilingbuddha
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Why do we usually not want the eigenvalues of non-symmetric matrices?

I came across this line in a class note I am reading where it discusses finding eigenvalues of matrices. In reality we don't go all the way with Arnoldi. We stop at a decent value of . Then the eigenvalues of are (usually) good approximations to …
CuriousMind
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Catastrophic cancellation in logsum

I'm trying to implement the following function in double-precision floating point with low relative error: $$\mathrm{logsum}(x,y) = \log(\exp(x) + \exp(y))$$ This is used extensively in statistical applications to add probabilities or probability…
Neil Toronto
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Difficulty with Spectral Method using Chebyshev Polynomials

I am having a bit of difficulty in trying to understand a paper. The paper uses spectral method to solve for an eigenvalue that comes from a system of coupled ODEs. I will write out only one equation now, because it is enough to get to the crux of…
tau1777
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Parallel Scientific Computation Software Development Language?

I want to develop a parallel scientific computation software from scratch. I want some thoughts on which language to start. The program involves reading/writing data to txt files and doing heavy computations in parallel, with many LU factorizations…
electrique
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Selecting most scattered points from a set of points

Is there any (efficient) algorithm to select subset of $M$ points from a set of $N$ points ($M < N$) such that they "cover" most area (over all possible subsets of size $M$)? I assume the points are in 2D plane. The naive algorithm is simple, but…
Libor
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