init — Initialize a preconditioner

call prec%init(icontxt,ptype, info)

Type:: Asynchronous.
On Entry
icontxt: the communication context.
Scope:global.
Type:required.
Intent: in.
Specified as: an integer value.
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 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 ptype string as follows⁴ :

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 A;
BJAC: Precondition by a factorization of the block-diagonal of matrix A, where block boundaries are determined by the data allocation boundaries for each process; requires no communication. Only the incomplete factorization ILU(0) is currently implemented.