# init — Initialize a preconditioner

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#### 10.1 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.

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