dcreate_diag_sdia 

Generate diagonal preconditioner for symmetric diagonal storage (Serial and Parallel Versions)

FORMAT

  DCREATE_DIAG_SDIA (a, ia, ndim, nz, p, 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.

  p                   real*8
                      On entry, a one-dimensional array of length at least n.
                      On exit, array P contains information for use by the
                      diagonal preconditioner.

  n                   integer*4
                      On entry, the order of the matrix A.
                      On exit, n is unchanged.

Description

  DCREATE_DIAG_SDIA computes the information required by the diagonal
  preconditioner for a sparse matrix stored using the symmetric diagonal
  storage scheme. The real part of this information is returned in the array
  P. There is no integer information returned for this preconditioner.

  The routine DCREATE_DIAG_SDIA is called prior to a call to one of the
  iterative solver routines with diagonal preconditioning.

  This routine is available in both serial and parallel versions. The routine
  names and parameter list are identical for both versions. For information
  about linking to the serial or to the parallel library, refer to the CXML
  Reference Manual.