Basic HTML version of Foils prepared 6 December 96

Foil 47 Banded LU Decomposition

From Full Matrices - December 4, 1995 CPS615 Basic Simulation Track for Computational Science -- Fall Semester 95. by Geoffrey C. Fox, Nancy J. McCracken


1 Suppose that the matrix A is banded with bandwidth b and half-width w, where b=2w-1.
2 The sequential algorithm is similar to the full matrix case, except at each stage only those elements within a computational "window" of w rows and w columns are updated.
3 Partial pivoting can cause the number of columns in the computational window to be greater than m. This necessitates some extra bookkeeping in both the sequential and parallel algorithms.
4 The parallel banded and full algorithms are similar, but use a different decomposition. To get better load balancing, a scattered decomposition over both rows and columns is used in the banded algorithm. In the full case, a scattered decomposition just over rows was used.

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© on Tue Oct 7 1997