Digital

Name

dcreate_ilu_udia − Generate incomplete LU preconditioner for unsymmetric diagonal storage

FORMAT

DCREATE_ILU_UDIA (a, ia, ndim, nz, plu, iplu, n)

Arguments

areal∗8
On entry, a two-dimensional array with dimensions ndim by 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 nz,  containing the distances of the diagonals from the main diagonal.
On exit, ia is unchanged. 

ndiminteger∗4
On entry, the leading dimension of array A, as declared in the calling subprogram; ndim >= n.
On exit, ndim is unchanged. 

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

plureal∗8
On entry, a two-dimensional array with dimensions ndim by nz.
On exit, array PLU contains information used by the Incomplete LU preconditioner.

ipluinteger∗4
On entry, a one-dimensional array of length at least nz.
On exit, array IPLU 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_UDIA computes the information required by the Incomplete LU preconditioner for a sparse matrix stored using the unsymmetric diagonal storage scheme. The arrays PLU and IPLU contain the real and integer information, respectively, for use by the preconditioner. 

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