PCCompositeType#

Determines how two or more preconditioner are composed with the PCType of PCCOMPOSITE

Synopsis#

typedef enum {
  PC_COMPOSITE_ADDITIVE,
  PC_COMPOSITE_MULTIPLICATIVE,
  PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE,
  PC_COMPOSITE_SPECIAL,
  PC_COMPOSITE_SCHUR,
  PC_COMPOSITE_GKB
} PCCompositeType;

Values#

PC_COMPOSITE_ADDITIVE - results from application of all preconditioners are added together
PC_COMPOSITE_MULTIPLICATIVE - preconditioners are applied sequentially to the residual freshly computed after the previous preconditioner application
PC_COMPOSITE_SYMMETRIC_MULTIPLICATIVE - preconditioners are applied sequentially to the residual freshly computed from first preconditioner to last and then back (Use only for symmetric matrices and preconditioners)
PC_COMPOSITE_SPECIAL - This is very special for a matrix of the form \( \alpha I + R + S\) where the first preconditioner is built from \(\alpha I + S\) and second from \(\alpha I + R\)
PC_COMPOSITE_SCHUR - composes the Schur complement of the matrix from two blocks, see PCFIELDSPLIT
PC_COMPOSITE_GKB - the generalized Golub-Kahan bidiagonalization preconditioner, see PCFIELDSPLIT