PCFieldSplitSchurPreType#

Determines how to precondition a Schur complement

Synopsis#

typedef enum {
  PC_FIELDSPLIT_SCHUR_PRE_SELF,
  PC_FIELDSPLIT_SCHUR_PRE_SELFP,
  PC_FIELDSPLIT_SCHUR_PRE_A11,
  PC_FIELDSPLIT_SCHUR_PRE_USER,
  PC_FIELDSPLIT_SCHUR_PRE_FULL
} PCFieldSplitSchurPreType;

Values#

PC_FIELDSPLIT_SCHUR_PRE_SELF - the preconditioner for the Schur complement is generated from the symbolic representation of the Schur complement matrix: The only preconditioner that currently works with this symbolic representation matrix object is PCLSC
PC_FIELDSPLIT_SCHUR_PRE_SELFP - the preconditioning for the Schur complement is generated from an explicitly-assembled approximation Sp = A11 - A10 inv(diag(A00)) A01 This is only a good preconditioner when diag(A00) is a good preconditioner for A00. Optionally, A00 can be lumped before extracting the diagonal using the additional option -fieldsplit_1_mat_schur_complement_ainv_type lump
PC_FIELDSPLIT_SCHUR_PRE_A11 - the preconditioner for the Schur complement is generated from the block diagonal part of the matrix used to define the preconditioner, associated with the Schur complement (i.e. A11), not the Schur complement matrix
PC_FIELDSPLIT_SCHUR_PRE_USER - the preconditioner for the Schur complement is generated from the user provided matrix (pre argument to this function).
PC_FIELDSPLIT_SCHUR_PRE_FULL - the preconditioner for the Schur complement is generated from the exact Schur complement matrix representation computed internally by PCFIELDSPLIT (this is expensive) useful mostly as a test that the Schur complement approach can work for your problem