dcreate_ilu_udia 

Generate incomplete LU preconditioner for unsymmetric diagonal storage

FORMAT

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

Arguments

  a                   real*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.

  ia                  integer*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.

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

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

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

  iplu                integer*4
                      On entry, a one-dimensional array of length at least
                      nz.
                      On exit, array IPLU contains information used by the
                      Incomplete LU preconditioner.

  n                   integer*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.