Basic HTML version of Foils prepared August 7 98

Foil 23 Conjugate Gradient: Communication

From DoD HPF Training -- 5. Parallel Programming in HPF DoD Training and Others -- 1995-98. by Chuck Koelbel -- Rice University
Convergence test:
  • Global reduction
Dot products:
  • Global reductions
Vector updates:
  • Elementwise scaling and addition of two vectors
  • No communication if vectors are aligned
Matrix-vector multiplies:
  • Depends on the matrix (PDE operator) in the problem
  • For the model problem, equivalent to Jacobi iteration grid update
  • Static, local communication

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