SRC/dlasyf_aa.f(3)         Library Functions Manual         SRC/dlasyf_aa.f(3)

NAME
       SRC/dlasyf_aa.f

SYNOPSIS
   Functions/Subroutines
       subroutine dlasyf_aa (uplo, j1, m, nb, a, lda, ipiv, h, ldh, work)
           DLASYF_AA

Function/Subroutine Documentation
   subroutine dlasyf_aa (character uplo, integer j1, integer m, integer nb,
       double precision, dimension( lda, * ) a, integer lda, integer,
       dimension( * ) ipiv, double precision, dimension( ldh, * ) h, integer
       ldh, double precision, dimension( * ) work)
       DLASYF_AA

       Purpose:


            DLATRF_AA factorizes a panel of a real 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
           UPLO

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

           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 DSYTRF_AA, for the first panel, J1 is 1,
                     while for the remaining panels, J1 is 2.

           M

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

           NB

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

           A

                     A is DOUBLE PRECISION 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.

           LDA

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

           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).

           H

                     H is DOUBLE PRECISION workspace, dimension (LDH,NB).

           LDH

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

           WORK

                     WORK is DOUBLE PRECISION workspace, dimension (M).

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 142 of file dlasyf_aa.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0              SRC/dlasyf_aa.f(3)