Matrix Factorization Overlap

Matrix factorization overlap = {char_string}

Description / Usage

This optional card determines how much matrix factorization overlap occurs with other processors. This specification is only relevant for parallel computations. The valid options for {char_string} are:

none

No augmentation is performed, equivalent to a setting of k=0. This is the default.

diag

Augment the processor’s local matrix to include the diagonal (MSR) or diagonal blocks (VBR) for external rows.

k

Augment the processor’s local matrix to include external rows. The rows are selected by examining non-zero columns from the current local system that refer to offprocessor unknowns, and including the rows associated with those off-processor unknowns. This process is repeated k times, where k > 0. When complete, all non-zero columns whose associated rows have not been included are discarded. A value of 0 is equivalent to a setting of none.

If the Matrix factorization overlap card is omitted, the default is none.

Examples

Following is a sample card:

Matrix factorization overlap = 1

Technical Discussion

This optional card determines how much a processor’s local matrix is to be augmented with information from adjacent processors during the approximate factorizations used to build preconditioners. This card should be omitted or given a value of none for serial executions.