Matrix Reorder#

Matrix reorder = {none | rcm}

Description / Usage#

This optional card determines whether RCM (Reverse Cuthill-McKee) reordering of the linear system is to be performed. Valid options are:


the equations are not reordered.


the equations are reordered using an RCM scheme.

If the Matrix reorder card is omitted, then the default selection is none.


Following is a sample card:

Matrix reorder = rcm

Technical Discussion#

Note that reordering frequently is helpful in achieving convergence for iterative solution of linear systems. In a few instances, however, Goma users have noted that RCM reordering hinders convergence for selected problems. The default for Goma is to not use the RCM reordering so that quantitatively comparable results are obtained using either Aztec 1 (which did not have RCM reordering as an option) or Aztec 2.x. In summary, users are encouraged to try RCM reordering when using iterative solvers, foregoing the option only as a further resort in the face of repeated convergence failures.