Digital

Name

dcreate_ilu_genr − Generate incomplete LU preconditioner for general storage by rows

FORMAT

DCREATE_ILU_GENR (a, ia, ja, nz, plu, n)

Arguments

areal∗8
On entry, a one-dimensional array of length at least nz containing the nonzero elements of the matrix A.
On exit, a is unchanged. 

iainteger∗4
On entry, a one-dimensional array of length at least n+1,  containing the starting indices of each row in arrays JA and A.
On exit, ia is unchanged. 

jainteger∗4
On entry, a one-dimensional array of length at least nz, containing the column values of each nonzero element of the  matrix A.
On exit, ja is unchanged. 

nzinteger∗4
On entry, the number of nonzero elements in array A.
On exit, nz is unchanged. 

plureal∗8
On entry, a one-dimensional array of length at least nz.
On exit, array PLU contains information used by the Incomplete LU preconditioner.

ninteger∗4
On entry, the order of the matrix A.
On exit, n is unchanged. 

Description

DCREATE_ILU_GENR computes the information required by the Incomplete LU preconditioner for a sparse matrix stored using the general storage by rows scheme. The array PLU contains the real information for use by the preconditioner. The integer information is identical to the information in arrays IA and JA and is therefore not generated. 

The routine DCREATE_ILU_GENR is called prior to a call to one of the iterative solver routines with Incomplete LU preconditioning.