Parallelization of Geodesic Ray-Tracing for Arbitrary Metrics - - PowerPoint PPT Presentation

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Parallelization of Geodesic Ray-Tracing for Arbitrary Metrics - - PowerPoint PPT Presentation

Nov 25, 2023 37 likes •213 views

CINESPA Parallelization of Geodesic Ray-Tracing for Arbitrary Metrics Guillermo Andree Oliva Mercado October 14, 2016 Space Science Research Centre (CINESPA) University of Costa Rica 1 Description of the problem Program and parallelization

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CINESPA

Parallelization of Geodesic Ray-Tracing for Arbitrary Metrics

Guillermo Andree Oliva Mercado October 14, 2016

Space Science Research Centre (CINESPA) University of Costa Rica 1

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Description of the problem

Program and parallelization The future

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What you need to know...

  • Metrics describe spacetime
  • Spacetime becomes curved around compact objects (neutron

stars, black holes, etc.)

  • Curved spacetime bends light: null geodesics
  • Geodesic equations: 2nd order ODE system that contains

derivatives of the metric that describe trajectories of particles

  • I am solving the geodesic equations for arbitrary metrics
  • I want to apply the result to:
  • Gravitational redshift of radiation emitted near a compact
  • bject ←
  • High resolution gravitational lenses

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Initial conditions

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Description of the problem

Program and parallelization

The future

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Structure of the program

generation of equations python/fortran interface Metric X geodesic equations (subroutines) variation of initial conditions

  • utput files

sage python fortran text/bin file module script numerical methods, coordinates analysis and visualization 7

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Problems with the serial version

  • For low resolutions works decently fine (aprox. 1-5 minutes)
  • Increasing the size of the region increases considerably the

time!

  • I need lots of runs! — Different parameters
  • Theoretically it’s easy to parallelize and use available resources

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Parallelizable tasks

generation of equations Metric X geodesic equations (subroutines) variation of initial conditions

  • utput files

sage python fortran text/bin file module script numerical methods, coordinates analysis and visualization parallelizable tasks 9

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Implementation

solving of geodesic equations distribution of initial conditions

  • utput files

data gathering and

  • utput

solving of geodesic equations distribution of initial conditions solving of geodesic equations distribution of initial conditions analysis and visualization

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Problems and simplifications

  • Distribution of initial conditions manually
  • Saving all iterations: with adaptive-size methods you can’t

predict the size of results!

  • The initial and final iterations allowed me to construct one

image

  • Non-perfect results (nothing to do with parallelization)

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Results

200 × 200 pixels

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Scalability

Numbers: processes in the x direction

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Description of the problem Program and parallelization

The future

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Lessons learned

  • All is more complicated in parallel
  • Ask questions!
  • Look for things already implemented!
  • Start with the simplest case
  • Prototyping in Python before implementing in the main code
  • Version control saved my life: In the past, I had already

implemented and erased some useful lines of code that I needed now!

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This School helped me because...

  • I can now generate higher resolution images and try more

initial conditions

  • I can now use the Chirripó cluster (Cinespa) for my project
  • It gave me an insight about parallel programing for other

projects

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Thanks

GANDREOLIVA more information www.gandreoliva.org/english

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