Data Layout



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Data Layout

The matrix and vectors are layed out in a simple block column fashion. The nodes are ordered in a natural order to minimize bandwidth and hence interprocessor communication. The columns () of the upper triangular portion of the symmetric matrix are layed out in blocks on the processors, the vector members () associated with the columns of the matrix are put on the same processor. The matrix-vector multiply requires that the members of the left hand side vector , which are in the same row as an array member stored on another processor, be communicated to carry out the computation. The right hand side result , then needs to be sent back to the same processor that sent the left hand side (because of the symmetry of ) - so that the final result can be calculated.



ADAMS
Thu May 18 11:22:16 PDT 1995