NVIDIA / NVIDIA/AMGX

Right-hand-side of Poisson examples should be changed

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#30 4 comments 0 reactions 0 assignees View on GitHub

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enhancement good first issue
Dominant language
Cuda
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692
Forks
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Description

AMGX ships with many nice sample programs, including simple implementation of Poisson-like equations. Currently, the charge function (e.g. in A x = b, the array b) is set to 1.d0 everywhere.

This is a poor choice, since integrating a constant over larger and large volumes gives you an exponentially growing solution. As a consequence, the sample cases have terrible convergence rates and do not scale as the problem size is increased.

I suggest a better choice: set b = sin( 2 * pi * x / Lx ) * sin( 2 * pi * y / Ly ) * sin( 2 * pi * z / Lz ), which satisfies either periodic or Dirichlet boundary conditions. This is more representative of the use of a Poisson solver.

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First steps

  1. Read the whole issue, then the project's contributing guide.
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  3. Fork the repository and make your change on a branch.
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Research direction

Start by locating the Poisson sample programs and the charge-function initialization described in the issue. Replace the constant right-hand side with the proposed sinusoidal form, then verify that the examples still support periodic or Dirichlet boundary conditions and show improved convergence as problem size increases.

Written by the indexing model from the issue text.

Assessment

Domain
hpc
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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