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## clasyf_aa()

subroutine clasyf_aa | ( | character | uplo,
|  | integer | j1,
|  | integer | m,
|  | integer | nb,
|  | complex, dimension( lda, * ) | a,
|  | integer | lda,
|  | integer, dimension( * ) | ipiv,
|  | complex, dimension( ldh, * ) | h,
|  | integer | ldh,
|  | complex, dimension( * ) | work )

CLASYF_AA

Download CLASYF_AA + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> DLATRF_AA factorizes a panel of a complex symmetric matrix A using
      !> the Aasen's algorithm. The panel consists of a set of NB rows of A
      !> when UPLO is U, or a set of NB columns when UPLO is L.
      !>
      !> In order to factorize the panel, the Aasen's algorithm requires the
      !> last row, or column, of the previous panel. The first row, or column,
      !> of A is set to be the first row, or column, of an identity matrix,
      !> which is used to factorize the first panel.
      !>
      !> The resulting J-th row of U, or J-th column of L, is stored in the
      !> (J-1)-th row, or column, of A (without the unit diagonals), while
      !> the diagonal and subdiagonal of A are overwritten by those of T.
      !>
      !>

Parameters

  [in]

  UPLO

      !>          UPLO is CHARACTER*1
      !>          = 'U':  Upper triangle of A is stored;
      !>          = 'L':  Lower triangle of A is stored.
      !>

  [in]

  J1

      !>          J1 is INTEGER
      !>          The location of the first row, or column, of the panel
      !>          within the submatrix of A, passed to this routine, e.g.,
      !>          when called by CSYTRF_AA, for the first panel, J1 is 1,
      !>          while for the remaining panels, J1 is 2.
      !>

  [in]

  M

      !>          M is INTEGER
      !>          The dimension of the submatrix. M >= 0.
      !>

  [in]

  NB

      !>          NB is INTEGER
      !>          The dimension of the panel to be facotorized.
      !>

  [in,out]

  A

      !>          A is COMPLEX array, dimension (LDA,M) for
      !>          the first panel, while dimension (LDA,M+1) for the
      !>          remaining panels.
      !>
      !>          On entry, A contains the last row, or column, of
      !>          the previous panel, and the trailing submatrix of A
      !>          to be factorized, except for the first panel, only
      !>          the panel is passed.
      !>
      !>          On exit, the leading panel is factorized.
      !>

  [in]

  LDA

      !>          LDA is INTEGER
      !>          The leading dimension of the array A.  LDA >= max(1,M).
      !>

  [out]

  IPIV

      !>          IPIV is INTEGER array, dimension (M)
      !>          Details of the row and column interchanges,
      !>          the row and column k were interchanged with the row and
      !>          column IPIV(k).
      !>

  [in,out]

  H

      !>          H is COMPLEX workspace, dimension (LDH,NB).
      !>
      !>

  [in]

  LDH

      !>          LDH is INTEGER
      !>          The leading dimension of the workspace H. LDH >= max(1,M).
      !>

  [out]

  WORK

      !>          WORK is COMPLEX workspace, dimension (M).
      !>

Author
  Univ. of Tennessee
  Univ. of California Berkeley
  Univ. of Colorado Denver
  NAG Ltd.