Analysis of Parallel Red Black Gauss Seidel

• This can be parallelized as easily as Jacobi!

  Phase I follows by Phase II.

• Red black is a different ordering from original Gauss Seidel.

• For (some) elliptic problems, can show red black as good as and maybe better than original ordering.

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  i.e., red black does not need more iterations than pure Gauss Seidel.

• For related hyperbolic problems---see NAS benchmark SSOR discussion in CPS713---not so clear.

• For higher order differencing, need more phases (more colors) but principle the same.

• Also not clear how to use if irregular matrix, as in sparse matrices from power systems.