~/talk

Tall-and-skinny QR Factorizations in MapReduce

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Runs 8,192 nonlinear heat-transfer simulations produce about 4.5 TB and get stitched into a 5 billion x 64 matrix (~2.2 TB) whose SVD yields reduced-order models that evaluate about 100× faster with roughly two digits of accuracy. QR is computed in Hadoop using a communication-avoiding TSQR (local QRs, reduce-tree of R factors), avoiding MPI; practical timings: reading 200 GB takes ~253 s, writing ~1,000 s, R by the new algorithm ~500 s, full orthogonal Q ~3,000 s.

AI-written summary · about

  1. 0:00Physics simulation overview
  2. 1:34Case study on heat transfer
  3. 4:10Matrix construction and SVD
  4. 6:19Advantages of model reduction
  5. 9:17Jet engine acoustic research
  6. 11:21Tall and skinny matrices
  7. 13:58MapReduce QR implementation
  8. 23:14Stabilizing QR algorithms
  9. 28:17Conclusion and references
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