Next: psb_precbld Builds Up: userhtml Previous: Preconditioner routines Contents

# psb_precinit -- Initialize a preconditioner

ifstarssyntaxsyntaxcall psb_precinitprec, ptype, info

Type:
  Asynchronous.
On Entry
ptype
  the type of preconditioner. Scope: global
  Type: required
  Intent: in.
  Specified as: a character string, see usage notes.
On Exit

prec
  Scope: local
  Type: required
  Intent: inout.
  Specified as: a preconditioner data structure precdata`psb_prec_type`.
info
  Scope: global
  Type: required
  Intent: out.
  Error code: if no error, 0 is returned.

Notes Legal inputs to this subroutine are interpreted depending on the string as follows3:

NONE
  No preconditioning, i.e. the preconditioner is just a copy operator.
DIAG
  Diagonal scaling; each entry of the input vector is multiplied by the reciprocal of the sum of the absolute values of the coefficients in the corresponding row of matrix ;
BJAC
  Precondition by a factorization of the block-diagonal of matrix , where block boundaries are determined by the data allocation boundaries for each process; requires no communication. Only the incomplete factorization is currently implemented.